91857981 has 8 divisors (see below), whose sum is σ = 123289024. Its totient is φ = 60832800.

The previous prime is 91857979. The next prime is 91858001. The reversal of 91857981 is 18975819.

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

It is not a de Polignac number, because 91857981 - 2¹ = 91857979 is a prime.

It is a super-2 number, since 2×91857981² = 16875777346792722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 91857981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91857901) 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, 100936 + ... + 101841.

It is an arithmetic number, because the mean of its divisors is an integer number (15411128).

Almost surely, 2^91857981 is an apocalyptic number.

It is an amenable number.

91857981 is a deficient number, since it is larger than the sum of its proper divisors (31431043).

91857981 is a wasteful number, since it uses less digits than its factorization.

91857981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202931.

The product of its digits is 181440, while the sum is 48.

The square root of 91857981 is about 9584.2569352037. The cubic root of 91857981 is about 451.2033324206.

The spelling of 91857981 in words is "ninety-one million, eight hundred fifty-seven thousand, nine hundred eighty-one".