81732791 has 4 divisors (see below), whose sum is σ = 93408912. Its totient is φ = 70056672.

The previous prime is 81732779. The next prime is 81732793. The reversal of 81732791 is 19723718.

It is a semiprime because it is the product of two primes.

It is a de Polignac number, because none of the positive numbers 2^k-81732791 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81732793) 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, 5838050 + ... + 5838063.

It is an arithmetic number, because the mean of its divisors is an integer number (23352228).

Almost surely, 2^81732791 is an apocalyptic number.

81732791 is a deficient number, since it is larger than the sum of its proper divisors (11676121).

81732791 is a wasteful number, since it uses less digits than its factorization.

81732791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11676120.

The product of its digits is 21168, while the sum is 38.

The square root of 81732791 is about 9040.6189500498. The cubic root of 81732791 is about 433.9757307672.

The spelling of 81732791 in words is "eighty-one million, seven hundred thirty-two thousand, seven hundred ninety-one".