81910079 has 4 divisors (see below), whose sum is σ = 81983760. Its totient is φ = 81836400.

The previous prime is 81910033. The next prime is 81910099. The reversal of 81910079 is 97001918.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81910079 is a prime.

It is a super-2 number, since 2×81910079² = 13418522083572482, 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 (81910099) 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, 35147 + ... + 37404.

It is an arithmetic number, because the mean of its divisors is an integer number (20495940).

Almost surely, 2^81910079 is an apocalyptic number.

81910079 is a deficient number, since it is larger than the sum of its proper divisors (73681).

81910079 is a wasteful number, since it uses less digits than its factorization.

81910079 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73680.

The product of its (nonzero) digits is 4536, while the sum is 35.

The square root of 81910079 is about 9050.4187195952. The cubic root of 81910079 is about 434.2892855664.

The spelling of 81910079 in words is "eighty-one million, nine hundred ten thousand, seventy-nine".