21404260 has 96 divisors (see below), whose sum is σ = 51609600. Its totient is φ = 7413120.

The previous prime is 21404213. The next prime is 21404263. The reversal of 21404260 is 6240412.

21404260 = T₃₇₇₆ + T₃₇₇₇ + T₃₇₇₈.

It is a super-2 number, since 2×21404260² = 916284692295200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is not an unprimeable number, because it can be changed into a prime (21404263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 270901 + ... + 270979.

It is an arithmetic number, because the mean of its divisors is an integer number (537600).

Almost surely, 2^21404260 is an apocalyptic number.

21404260 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21404260 is the 3778-th centered triangular number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21404260, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25804800).

21404260 is an abundant number, since it is smaller than the sum of its proper divisors (30205340).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21404260 is a wasteful number, since it uses less digits than its factorization.

21404260 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161 (or 159 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 21404260 is about 4626.4738192278. The cubic root of 21404260 is about 277.6515310162.

Multiplying 21404260 by its sum of digits (19), we get a triangular number (406680940 = T₂₈₅₁₉).

Adding to 21404260 its reverse (6240412), we get a palindrome (27644672).

It can be divided in two parts, 2140 and 4260, that added together give a square (6400 = 80²).

The spelling of 21404260 in words is "twenty-one million, four hundred four thousand, two hundred sixty".