81467991 has 32 divisors (see below), whose sum is σ = 138604800. Its totient is φ = 46772640.

The previous prime is 81467987. The next prime is 81467993. The reversal of 81467991 is 19976418.

It is a happy number.

It is not a de Polignac number, because 81467991 - 2² = 81467987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81467993) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1576 + ... + 12861.

It is an arithmetic number, because the mean of its divisors is an integer number (4331400).

Almost surely, 2^81467991 is an apocalyptic number.

81467991 is a deficient number, since it is larger than the sum of its proper divisors (57136809).

81467991 is a wasteful number, since it uses less digits than its factorization.

81467991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14476 (or 14470 counting only the distinct ones).

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

The square root of 81467991 is about 9025.9620539863. The cubic root of 81467991 is about 433.5065551385.

The spelling of 81467991 in words is "eighty-one million, four hundred sixty-seven thousand, nine hundred ninety-one".