639090 has 48 divisors (see below), whose sum is σ = 1729728. Its totient is φ = 169776.

The previous prime is 639083. The next prime is 639091. The reversal of 639090 is 90936.

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (639091) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2299 + ... + 2561.

It is an arithmetic number, because the mean of its divisors is an integer number (36036).

2⁶³⁹⁰⁹⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (864864).

639090 is an abundant number, since it is smaller than the sum of its proper divisors (1090638).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

639090 is a wasteful number, since it uses less digits than its factorization.

639090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 285 (or 273 counting only the distinct ones).

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

The square root of 639090 is about 799.4310476833. The cubic root of 639090 is about 86.1365237364.

The spelling of 639090 in words is "six hundred thirty-nine thousand, ninety".