21052040 has 32 divisors (see below), whose sum is σ = 47499480. Its totient is φ = 8397312.

The previous prime is 21052039. The next prime is 21052043. The reversal of 21052040 is 4025012.

It can be written as a sum of positive squares in 4 ways, for example, as 5354596 + 15697444 = 2314^2 + 3962^2 .

It is not an unprimeable number, because it can be changed into a prime (21052043) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24254 + ... + 25106.

Almost surely, 2^21052040 is an apocalyptic number.

21052040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21052040 is an abundant number, since it is smaller than the sum of its proper divisors (26447440).

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

21052040 is a wasteful number, since it uses less digits than its factorization.

21052040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1481 (or 1477 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 14.

The square root of 21052040 is about 4588.2502111371. The cubic root of 21052040 is about 276.1201255431.

Adding to 21052040 its reverse (4025012), we get a palindrome (25077052).

The spelling of 21052040 in words is "twenty-one million, fifty-two thousand, forty".