90905 has 4 divisors (see below), whose sum is σ = 109092. Its totient is φ = 72720.

The previous prime is 90901. The next prime is 90907. The reversal of 90905 is 50909.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 64009 + 26896 = 253^2 + 164^2 .

It is not a de Polignac number, because 90905 - 2² = 90901 is a prime.

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

It is a Duffinian number.

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, 9086 + ... + 9095.

It is an arithmetic number, because the mean of its divisors is an integer number (27273).

2⁹⁰⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

90905 is a deficient number, since it is larger than the sum of its proper divisors (18187).

90905 is a wasteful number, since it uses less digits than its factorization.

90905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18186.

The product of its (nonzero) digits is 405, while the sum is 23.

The square root of 90905 is about 301.5045604962. The cubic root of 90905 is about 44.9637568257.

The spelling of 90905 in words is "ninety thousand, nine hundred five".