642904 has 8 divisors (see below), whose sum is σ = 1205460. Its totient is φ = 321448.

The previous prime is 642899. The next prime is 642907. The reversal of 642904 is 409246.

It is a tau number, because it is divible by the number of its divisors (8).

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40174 + ... + 40189.

2⁶⁴²⁹⁰⁴ is an apocalyptic number.

It is an amenable number.

642904 is a deficient number, since it is larger than the sum of its proper divisors (562556).

642904 is a wasteful number, since it uses less digits than its factorization.

642904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80369 (or 80365 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 642904 is about 801.8129457673. The cubic root of 642904 is about 86.3075342513.

The spelling of 642904 in words is "six hundred forty-two thousand, nine hundred four".