643992 has 16 divisors (see below), whose sum is σ = 1610040. Its totient is φ = 214656.

The previous prime is 643991. The next prime is 644009. The reversal of 643992 is 299346.

643992 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643991) 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, 13393 + ... + 13440.

2⁶⁴³⁹⁹² is an apocalyptic number.

It is an amenable number.

643992 is an abundant number, since it is smaller than the sum of its proper divisors (966048).

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

643992 is a wasteful number, since it uses less digits than its factorization.

643992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26842 (or 26838 counting only the distinct ones).

The product of its digits is 11664, while the sum is 33.

The square root of 643992 is about 802.4911214462. The cubic root of 643992 is about 86.3561934994.

The spelling of 643992 in words is "six hundred forty-three thousand, nine hundred ninety-two".