90921 has 4 divisors (see below), whose sum is σ = 121232. Its totient is φ = 60612.

The previous prime is 90917. The next prime is 90931. The reversal of 90921 is 12909.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 90921 - 2² = 90917 is a prime.

It is a D-number.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

90921 is a lucky number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 90921.

It is not an unprimeable number, because it can be changed into a prime (90901) 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, 15151 + ... + 15156.

It is an arithmetic number, because the mean of its divisors is an integer number (30308).

2⁹⁰⁹²¹ is an apocalyptic number.

It is an amenable number.

90921 is a deficient number, since it is larger than the sum of its proper divisors (30311).

90921 is a wasteful number, since it uses less digits than its factorization.

90921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30310.

The product of its (nonzero) digits is 162, while the sum is 21.

The square root of 90921 is about 301.5310929241. The cubic root of 90921 is about 44.9663946634.

The spelling of 90921 in words is "ninety thousand, nine hundred twenty-one".