21620056 has 32 divisors (see below), whose sum is σ = 43932240. Its totient is φ = 9934848.

The previous prime is 21620021. The next prime is 21620059. The reversal of 21620056 is 65002612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21620059) 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, 4000 + ... + 7696.

Almost surely, 2^21620056 is an apocalyptic number.

It is an amenable number.

21620056 is an abundant number, since it is smaller than the sum of its proper divisors (22312184).

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

21620056 is a wasteful number, since it uses less digits than its factorization.

21620056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3763 (or 3759 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21620056 is about 4649.7371968747. The cubic root of 21620056 is about 278.5814993761.

Adding to 21620056 its reverse (65002612), we get a palindrome (86622668).

It can be divided in two parts, 216 and 20056, that multiplied together give a triangular number (4332096 = T₂₉₄₃).

The spelling of 21620056 in words is "twenty-one million, six hundred twenty thousand, fifty-six".