81581931231 has 8 divisors (see below), whose sum is σ = 112284808704. Its totient is φ = 52633503960.

The previous prime is 81581931203. The next prime is 81581931271. The reversal of 81581931231 is 13213918518.

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

It is not a de Polignac number, because 81581931231 - 2⁵ = 81581931199 is a prime.

It is a super-2 number, since 2×81581931231² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81581931271) 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, 438612441 + ... + 438612626.

It is an arithmetic number, because the mean of its divisors is an integer number (14035601088).

Almost surely, 2^81581931231 is an apocalyptic number.

81581931231 is a deficient number, since it is larger than the sum of its proper divisors (30702877473).

81581931231 is a wasteful number, since it uses less digits than its factorization.

81581931231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 877225101.

The product of its digits is 51840, while the sum is 42.

The spelling of 81581931231 in words is "eighty-one billion, five hundred eighty-one million, nine hundred thirty-one thousand, two hundred thirty-one".