644942 has 8 divisors (see below), whose sum is σ = 982056. Its totient is φ = 317592.

The previous prime is 644933. The next prime is 644951. The reversal of 644942 is 249446.

It is an interprime number because it is at equal distance from previous prime (644933) and next prime (644951).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

644942 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 3 ways as a sum of consecutive naturals, for example, 2273 + ... + 2540.

It is an arithmetic number, because the mean of its divisors is an integer number (122757).

2⁶⁴⁴⁹⁴² is an apocalyptic number.

644942 is a deficient number, since it is larger than the sum of its proper divisors (337114).

644942 is a wasteful number, since it uses less digits than its factorization.

644942 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4882.

The product of its digits is 6912, while the sum is 29.

The square root of 644942 is about 803.0828101759. The cubic root of 644942 is about 86.3986360953.

The spelling of 644942 in words is "six hundred forty-four thousand, nine hundred forty-two".