81617100020651 has 4 divisors (see below), whose sum is σ = 87895338483792. Its totient is φ = 75338861557512.

The previous prime is 81617100020641. The next prime is 81617100020653. The reversal of 81617100020651 is 15602000171618.

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

It is a cyclic number.

It is not a de Polignac number, because 81617100020651 - 2⁶ = 81617100020587 is a prime.

It is a super-2 number, since 2×81617100020651² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81617100020653) 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, 3139119231551 + ... + 3139119231576.

It is an arithmetic number, because the mean of its divisors is an integer number (21973834620948).

Almost surely, 2^{81617100020651} is an apocalyptic number.

81617100020651 is a deficient number, since it is larger than the sum of its proper divisors (6278238463141).

81617100020651 is a wasteful number, since it uses less digits than its factorization.

81617100020651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6278238463140.

The product of its (nonzero) digits is 20160, while the sum is 38.

The spelling of 81617100020651 in words is "eighty-one trillion, six hundred seventeen billion, one hundred million, twenty thousand, six hundred fifty-one".