91079981 has 8 divisors (see below), whose sum is σ = 94714680. Its totient is φ = 87478272.

The previous prime is 91079959. The next prime is 91079987. The reversal of 91079981 is 18997019.

It can be written as a sum of positive squares in 4 ways, for example, as 26357956 + 64722025 = 5134^2 + 8045^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 91079981 - 2²⁶ = 23971117 is a prime.

It is a super-2 number, since 2×91079981² = 16591125877920722, 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 (91079987) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2540 + ... + 13733.

It is an arithmetic number, because the mean of its divisors is an integer number (11839335).

Almost surely, 2^91079981 is an apocalyptic number.

It is an amenable number.

91079981 is a deficient number, since it is larger than the sum of its proper divisors (3634699).

91079981 is a wasteful number, since it uses less digits than its factorization.

91079981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16495.

The product of its (nonzero) digits is 40824, while the sum is 44.

The square root of 91079981 is about 9543.5832369189. The cubic root of 91079981 is about 449.9258824433.

The spelling of 91079981 in words is "ninety-one million, seventy-nine thousand, nine hundred eighty-one".