90891 has 6 divisors (see below), whose sum is σ = 131300. Its totient is φ = 60588.

The previous prime is 90887. The next prime is 90901. The reversal of 90891 is 19809.

It is not a de Polignac number, because 90891 - 2² = 90887 is a prime.

It is a super-2 number, since 2×90891² = 16522347762, which contains 22 as substring.

It is a Duffinian number.

90891 is a modest number, since divided by 891 gives 9 as remainder.

90891 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (90821) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5041 + ... + 5058.

2⁹⁰⁸⁹¹ is an apocalyptic number.

90891 is a deficient number, since it is larger than the sum of its proper divisors (40409).

90891 is a wasteful number, since it uses less digits than its factorization.

90891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10105 (or 10102 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 90891 is about 301.4813427063. The cubic root of 90891 is about 44.9614484638.

It can be divided in two parts, 908 and 91, that multiplied together give a palindrome (82628).

The spelling of 90891 in words is "ninety thousand, eight hundred ninety-one".