21523056 has 20 divisors (see below), whose sum is σ = 55601352. Its totient is φ = 7174336.

The previous prime is 21523049. The next prime is 21523063. The reversal of 21523056 is 65032512.

It is an interprime number because it is at equal distance from previous prime (21523049) and next prime (21523063).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 224151 + ... + 224246.

Almost surely, 2^21523056 is an apocalyptic number.

It is an amenable number.

21523056 is an abundant number, since it is smaller than the sum of its proper divisors (34078296).

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

21523056 is a wasteful number, since it uses less digits than its factorization.

21523056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 448408 (or 448402 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 24.

The square root of 21523056 is about 4639.2947739931. The cubic root of 21523056 is about 278.1642491594.

Adding to 21523056 its reverse (65032512), we get a palindrome (86555568).

The spelling of 21523056 in words is "twenty-one million, five hundred twenty-three thousand, fifty-six".