21053724 has 24 divisors (see below), whose sum is σ = 49208208. Its totient is φ = 7006080.

The previous prime is 21053713. The next prime is 21053731. The reversal of 21053724 is 42735012.

It is a junction number, because it is equal to n+sod(n) for n = 21053694 and 21053703.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8784 + ... + 10920.

It is an arithmetic number, because the mean of its divisors is an integer number (2050342).

Almost surely, 2^21053724 is an apocalyptic number.

It is an amenable number.

21053724 is an abundant number, since it is smaller than the sum of its proper divisors (28154484).

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

21053724 is a wasteful number, since it uses less digits than its factorization.

21053724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2965 (or 2963 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 24.

The square root of 21053724 is about 4588.4337196913. The cubic root of 21053724 is about 276.1274878366.

Adding to 21053724 its reverse (42735012), we get a palindrome (63788736).

The spelling of 21053724 in words is "twenty-one million, fifty-three thousand, seven hundred twenty-four".