21616531660 has 24 divisors (see below), whose sum is σ = 45401317920. Its totient is φ = 8645355264.

The previous prime is 21616531633. The next prime is 21616531661. The reversal of 21616531660 is 6613561612.

It is not an unprimeable number, because it can be changed into a prime (21616531661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 69156 + ... + 219124.

It is an arithmetic number, because the mean of its divisors is an integer number (1891721580).

Almost surely, 2^21616531660 is an apocalyptic number.

21616531660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21616531660 is an abundant number, since it is smaller than the sum of its proper divisors (23784786260).

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

21616531660 is a wasteful number, since it uses less digits than its factorization.

21616531660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157185 (or 157183 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 37.

The spelling of 21616531660 in words is "twenty-one billion, six hundred sixteen million, five hundred thirty-one thousand, six hundred sixty".