639654 has 32 divisors (see below), whose sum is σ = 1397760. Its totient is φ = 194400.

The previous prime is 639647. The next prime is 639671. The reversal of 639654 is 456936.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 639654.

It is an unprimeable number.

639654 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3444 + ... + 3624.

It is an arithmetic number, because the mean of its divisors is an integer number (43680).

2⁶³⁹⁶⁵⁴ is an apocalyptic number.

639654 is an abundant number, since it is smaller than the sum of its proper divisors (758106).

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

639654 is a wasteful number, since it uses less digits than its factorization.

639654 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236.

The product of its digits is 19440, while the sum is 33.

The square root of 639654 is about 799.7837207646. The cubic root of 639654 is about 86.1618549184.

The spelling of 639654 in words is "six hundred thirty-nine thousand, six hundred fifty-four".