90639 has 12 divisors (see below), whose sum is σ = 136136. Its totient is φ = 60264.

The previous prime is 90631. The next prime is 90641. The reversal of 90639 is 93609.

90639 is an esthetic number in base 13, because in such base its adjacent digits differ by 1.

It is not a de Polignac number, because 90639 - 2³ = 90631 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90631) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 57 + ... + 429.

2⁹⁰⁶³⁹ is an apocalyptic number.

90639 is a deficient number, since it is larger than the sum of its proper divisors (45497).

90639 is an equidigital number, since it uses as much as digits as its factorization.

90639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 388 (or 376 counting only the distinct ones).

The product of its (nonzero) digits is 1458, while the sum is 27.

The square root of 90639 is about 301.0631163062. The cubic root of 90639 is about 44.9198573549.

It can be divided in two parts, 90 and 639, that added together give a 6-th power (729 = 3⁶).

The spelling of 90639 in words is "ninety thousand, six hundred thirty-nine".