21637968665502 has 64 divisors (see below), whose sum is σ = 53030400952320. Its totient is φ = 5744960073216.

The previous prime is 21637968665497. The next prime is 21637968665543. The reversal of 21637968665502 is 20556686973612.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 191749153 + ... + 191861964.

It is an arithmetic number, because the mean of its divisors is an integer number (828600014880).

Almost surely, 2^{21637968665502} is an apocalyptic number.

21637968665502 is an abundant number, since it is smaller than the sum of its proper divisors (31392432286818).

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

21637968665502 is a wasteful number, since it uses less digits than its factorization.

21637968665502 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 383611225.

The product of its (nonzero) digits is 195955200, while the sum is 66.

The spelling of 21637968665502 in words is "twenty-one trillion, six hundred thirty-seven billion, nine hundred sixty-eight million, six hundred sixty-five thousand, five hundred two".