21356216170665 has 32 divisors (see below), whose sum is σ = 35698920099840. Its totient is φ = 10881527338176.

The previous prime is 21356216170591. The next prime is 21356216170669. The reversal of 21356216170665 is 56607161265312.

It is a happy number.

It is not a de Polignac number, because 21356216170665 - 2⁸ = 21356216170409 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21356216170669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 37323645 + ... + 37891514.

It is an arithmetic number, because the mean of its divisors is an integer number (1115591253120).

Almost surely, 2^{21356216170665} is an apocalyptic number.

It is an amenable number.

21356216170665 is a deficient number, since it is larger than the sum of its proper divisors (14342703929175).

21356216170665 is a wasteful number, since it uses less digits than its factorization.

21356216170665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75216013.

The product of its (nonzero) digits is 2721600, while the sum is 51.

The spelling of 21356216170665 in words is "twenty-one trillion, three hundred fifty-six billion, two hundred sixteen million, one hundred seventy thousand, six hundred sixty-five".