81616186751 has 4 divisors (see below), whose sum is σ = 89035840104. Its totient is φ = 74196533400.

The previous prime is 81616186723. The next prime is 81616186753. The reversal of 81616186751 is 15768161618.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 81616186751 - 2²⁶ = 81549077887 is a prime.

It is a super-2 number, since 2×81616186751² (a number of 23 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 81616186751.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81616186753) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3709826660 + ... + 3709826681.

It is an arithmetic number, because the mean of its divisors is an integer number (22258960026).

Almost surely, 2^81616186751 is an apocalyptic number.

81616186751 is a deficient number, since it is larger than the sum of its proper divisors (7419653353).

81616186751 is a wasteful number, since it uses less digits than its factorization.

81616186751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7419653352.

The product of its digits is 483840, while the sum is 50.

The spelling of 81616186751 in words is "eighty-one billion, six hundred sixteen million, one hundred eighty-six thousand, seven hundred fifty-one".