81630660731 has 4 divisors (see below), whose sum is σ = 81669889464. Its totient is φ = 81591432000.

The previous prime is 81630660679. The next prime is 81630660779. The reversal of 81630660731 is 13706603618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13706603618 = 2 ⋅6853301809.

It is a cyclic number.

It is not a de Polignac number, because 81630660731 - 2³⁴ = 64450791547 is a prime.

It is a super-2 number, since 2×81630660731² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81630663731) 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, 19611245 + ... + 19615406.

It is an arithmetic number, because the mean of its divisors is an integer number (20417472366).

Almost surely, 2^81630660731 is an apocalyptic number.

81630660731 is a deficient number, since it is larger than the sum of its proper divisors (39228733).

81630660731 is a wasteful number, since it uses less digits than its factorization.

81630660731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39228732.

The product of its (nonzero) digits is 108864, while the sum is 41.

The spelling of 81630660731 in words is "eighty-one billion, six hundred thirty million, six hundred sixty thousand, seven hundred thirty-one".