21658096660 has 24 divisors (see below), whose sum is σ = 46591321896. Its totient is φ = 8451939840.

The previous prime is 21658096657. The next prime is 21658096693. The reversal of 21658096660 is 6669085612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1004382864 + 20653713796 = 31692^2 + 143714^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13205337 + ... + 13206976.

It is an arithmetic number, because the mean of its divisors is an integer number (1941305079).

Almost surely, 2^21658096660 is an apocalyptic number.

21658096660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21658096660 is an abundant number, since it is smaller than the sum of its proper divisors (24933225236).

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

21658096660 is a wasteful number, since it uses less digits than its factorization.

21658096660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26412363 (or 26412361 counting only the distinct ones).

The product of its (nonzero) digits is 933120, while the sum is 49.

The spelling of 21658096660 in words is "twenty-one billion, six hundred fifty-eight million, ninety-six thousand, six hundred sixty".