21354551257165 has 16 divisors (see below), whose sum is σ = 29287136253312. Its totient is φ = 14642673597504.

The previous prime is 21354551257159. The next prime is 21354551257241. The reversal of 21354551257165 is 56175215545312.

It is a cyclic number.

It is not a de Polignac number, because 21354551257165 - 2⁷ = 21354551257037 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8153719 + ... + 10449508.

It is an arithmetic number, because the mean of its divisors is an integer number (1830446015832).

Almost surely, 2^{21354551257165} is an apocalyptic number.

It is an amenable number.

21354551257165 is a deficient number, since it is larger than the sum of its proper divisors (7932584996147).

21354551257165 is a wasteful number, since it uses less digits than its factorization.

21354551257165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18636036.

The product of its digits is 6300000, while the sum is 52.

The spelling of 21354551257165 in words is "twenty-one trillion, three hundred fifty-four billion, five hundred fifty-one million, two hundred fifty-seven thousand, one hundred sixty-five".