21516572020 has 48 divisors (see below), whose sum is σ = 45368346240. Its totient is φ = 8571744896.

The previous prime is 21516572017. The next prime is 21516572057. The reversal of 21516572020 is 2027561512.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5783721 + ... + 5787439.

It is an arithmetic number, because the mean of its divisors is an integer number (945173880).

Almost surely, 2^21516572020 is an apocalyptic number.

21516572020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21516572020 is an abundant number, since it is smaller than the sum of its proper divisors (23851774220).

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

21516572020 is a wasteful number, since it uses less digits than its factorization.

21516572020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4824 (or 4822 counting only the distinct ones).

The product of its (nonzero) digits is 8400, while the sum is 31.

The spelling of 21516572020 in words is "twenty-one billion, five hundred sixteen million, five hundred seventy-two thousand, twenty".