21512205070165 has 32 divisors (see below), whose sum is σ = 26067557376000. Its totient is φ = 17042206126848.

The previous prime is 21512205070133. The next prime is 21512205070199. The reversal of 21512205070165 is 56107050221512.

It is a cyclic number.

It is not a de Polignac number, because 21512205070165 - 2⁵ = 21512205070133 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 168422796 + ... + 168550474.

It is an arithmetic number, because the mean of its divisors is an integer number (814611168000).

Almost surely, 2^{21512205070165} is an apocalyptic number.

It is an amenable number.

21512205070165 is a deficient number, since it is larger than the sum of its proper divisors (4555352305835).

21512205070165 is a wasteful number, since it uses less digits than its factorization.

21512205070165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128709.

The product of its (nonzero) digits is 42000, while the sum is 37.

Adding to 21512205070165 its reverse (56107050221512), we get a palindrome (77619255291677).

The spelling of 21512205070165 in words is "twenty-one trillion, five hundred twelve billion, two hundred five million, seventy thousand, one hundred sixty-five".