21520208136 has 32 divisors (see below), whose sum is σ = 61486309440. Its totient is φ = 6148630848.

The previous prime is 21520208119. The next prime is 21520208137. The reversal of 21520208136 is 63180202512.

It is not an unprimeable number, because it can be changed into a prime (21520208137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64048071 + ... + 64048406.

It is an arithmetic number, because the mean of its divisors is an integer number (1921447170).

Almost surely, 2^21520208136 is an apocalyptic number.

It is an amenable number.

21520208136 is an abundant number, since it is smaller than the sum of its proper divisors (39966101304).

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

21520208136 is a wasteful number, since it uses less digits than its factorization.

21520208136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128096493 (or 128096489 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 30.

The spelling of 21520208136 in words is "twenty-one billion, five hundred twenty million, two hundred eight thousand, one hundred thirty-six".