81576631 has 4 divisors (see below), whose sum is σ = 83312352. Its totient is φ = 79840912.

The previous prime is 81576613. The next prime is 81576637. The reversal of 81576631 is 13667518.

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 81576631 - 2⁹ = 81576119 is a prime.

It is a super-2 number, since 2×81576631² = 13309493450620322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81576637) 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, 867790 + ... + 867883.

It is an arithmetic number, because the mean of its divisors is an integer number (20828088).

Almost surely, 2^81576631 is an apocalyptic number.

81576631 is a deficient number, since it is larger than the sum of its proper divisors (1735721).

81576631 is a wasteful number, since it uses less digits than its factorization.

81576631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1735720.

The product of its digits is 30240, while the sum is 37.

The square root of 81576631 is about 9031.9782439951. The cubic root of 81576631 is about 433.6991675267.

The spelling of 81576631 in words is "eighty-one million, five hundred seventy-six thousand, six hundred thirty-one".