81608647631 has 8 divisors (see below), whose sum is σ = 93299854464. Its totient is φ = 69925647960.

The previous prime is 81608647609. The next prime is 81608647643. The reversal of 81608647631 is 13674680618.

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

It is not a de Polignac number, because 81608647631 - 2¹⁸ = 81608385487 is a prime.

It is a super-2 number, since 2×81608647631² (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 81608647631.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81608647691) 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, 2030465 + ... + 2070266.

It is an arithmetic number, because the mean of its divisors is an integer number (11662481808).

Almost surely, 2^81608647631 is an apocalyptic number.

81608647631 is a deficient number, since it is larger than the sum of its proper divisors (11691206833).

81608647631 is a wasteful number, since it uses less digits than its factorization.

81608647631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4103581.

The product of its (nonzero) digits is 1161216, while the sum is 50.

The spelling of 81608647631 in words is "eighty-one billion, six hundred eight million, six hundred forty-seven thousand, six hundred thirty-one".