21651066120165 has 16 divisors (see below), whose sum is σ = 34645884221376. Its totient is φ = 11545842454400.

The previous prime is 21651066120161. The next prime is 21651066120169. The reversal of 21651066120165 is 56102166015612.

It is an interprime number because it is at equal distance from previous prime (21651066120161) and next prime (21651066120169).

It is not a de Polignac number, because 21651066120165 - 2² = 21651066120161 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21651066120161) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 86922096 + ... + 87170825.

It is an arithmetic number, because the mean of its divisors is an integer number (2165367763836).

Almost surely, 2^{21651066120165} is an apocalyptic number.

It is an amenable number.

21651066120165 is a deficient number, since it is larger than the sum of its proper divisors (12994818101211).

21651066120165 is a wasteful number, since it uses less digits than its factorization.

21651066120165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174101220.

The product of its (nonzero) digits is 129600, while the sum is 42.

The spelling of 21651066120165 in words is "twenty-one trillion, six hundred fifty-one billion, sixty-six million, one hundred twenty thousand, one hundred sixty-five".