81979090 has 32 divisors (see below), whose sum is σ = 153135360. Its totient is φ = 31574400.

The previous prime is 81979081. The next prime is 81979099. The reversal of 81979090 is 9097918.

It is an interprime number because it is at equal distance from previous prime (81979081) and next prime (81979099).

It is not an unprimeable number, because it can be changed into a prime (81979099) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31125 + ... + 33655.

It is an arithmetic number, because the mean of its divisors is an integer number (4785480).

Almost surely, 2^81979090 is an apocalyptic number.

81979090 is a deficient number, since it is larger than the sum of its proper divisors (71156270).

81979090 is a wasteful number, since it uses less digits than its factorization.

81979090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2658.

The product of its (nonzero) digits is 40824, while the sum is 43.

The square root of 81979090 is about 9054.2305029196. The cubic root of 81979090 is about 434.4112173449.

The spelling of 81979090 in words is "eighty-one million, nine hundred seventy-nine thousand, ninety".