81616540312551 has 8 divisors (see below), whose sum is σ = 108822140616304. Its totient is φ = 54410983441920.

The previous prime is 81616540312493. The next prime is 81616540312583. The reversal of 81616540312551 is 15521304561618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81616540312551 - 2²⁵ = 81616506758119 is a prime.

It is a super-2 number, since 2×81616540312551² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81616540312551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81616540112551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6186490 + ... + 14195271.

It is an arithmetic number, because the mean of its divisors is an integer number (13602767577038).

Almost surely, 2^{81616540312551} is an apocalyptic number.

81616540312551 is a deficient number, since it is larger than the sum of its proper divisors (27205600303753).

81616540312551 is a wasteful number, since it uses less digits than its factorization.

81616540312551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21716561.

The product of its (nonzero) digits is 864000, while the sum is 48.

The spelling of 81616540312551 in words is "eighty-one trillion, six hundred sixteen billion, five hundred forty million, three hundred twelve thousand, five hundred fifty-one".