81679491 has 12 divisors (see below), whose sum is σ = 118499680. Its totient is φ = 54213840.

The previous prime is 81679487. The next prime is 81679501. The reversal of 81679491 is 19497618.

It is a happy number.

It is not a de Polignac number, because 81679491 - 2² = 81679487 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81679471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17755 + ... + 21876.

Almost surely, 2^81679491 is an apocalyptic number.

81679491 is a deficient number, since it is larger than the sum of its proper divisors (36820189).

81679491 is a wasteful number, since it uses less digits than its factorization.

81679491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39866 (or 39863 counting only the distinct ones).

The product of its digits is 108864, while the sum is 45.

The square root of 81679491 is about 9037.6706622890. The cubic root of 81679491 is about 433.8813747726.

The spelling of 81679491 in words is "eighty-one million, six hundred seventy-nine thousand, four hundred ninety-one".