21098040 has 64 divisors (see below), whose sum is σ = 63914400. Its totient is φ = 5571072.

The previous prime is 21098017. The next prime is 21098047. The reversal of 21098040 is 4089012.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21098040.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21098047) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12274 + ... + 13886.

Almost surely, 2^21098040 is an apocalyptic number.

21098040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21098040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31957200).

21098040 is an abundant number, since it is smaller than the sum of its proper divisors (42816360).

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

21098040 is a wasteful number, since it uses less digits than its factorization.

21098040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1736 (or 1732 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 21098040 is about 4593.2602800190. The cubic root of 21098040 is about 276.3210923818.

Subtracting from 21098040 its reverse (4089012), we obtain a triangular number (17009028 = T₅₈₃₂).

The spelling of 21098040 in words is "twenty-one million, ninety-eight thousand, forty".