21041280 has 192 divisors, whose sum is σ = 78525720. Its totient is φ = 5160960.

The previous prime is 21041263. The next prime is 21041299. The reversal of 21041280 is 8214012.

It can be written as a sum of positive squares in 4 ways, for example, as 14930496 + 6110784 = 3864^2 + 2472^2 .

It is a tau number, because it is divible by the number of its divisors (192).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 74740 + ... + 75020.

Almost surely, 2^21041280 is an apocalyptic number.

21041280 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 21041280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39262860).

21041280 is an abundant number, since it is smaller than the sum of its proper divisors (57484440).

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

21041280 is a wasteful number, since it uses less digits than its factorization.

21041280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319 (or 304 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 21041280 is about 4587.0775009803. The cubic root of 21041280 is about 276.0730745387.

Adding to 21041280 its reverse (8214012), we get a palindrome (29255292).

It can be divided in two parts, 21041 and 280, that added together give a triangular number (21321 = T₂₀₆).

The spelling of 21041280 in words is "twenty-one million, forty-one thousand, two hundred eighty".