644694 has 8 divisors (see below), whose sum is σ = 1289400. Its totient is φ = 214896.

The previous prime is 644687. The next prime is 644701. The reversal of 644694 is 496446.

It is an interprime number because it is at equal distance from previous prime (644687) and next prime (644701).

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

644694 is an admirable number.

It is a congruent number.

It is an unprimeable number.

644694 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 in 3 ways as a sum of consecutive naturals, for example, 53719 + ... + 53730.

It is an arithmetic number, because the mean of its divisors is an integer number (161175).

2⁶⁴⁴⁶⁹⁴ is an apocalyptic number.

644694 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

644694 is a wasteful number, since it uses less digits than its factorization.

644694 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107454.

The product of its digits is 20736, while the sum is 33.

The square root of 644694 is about 802.9283903313. The cubic root of 644694 is about 86.3875603661.

The spelling of 644694 in words is "six hundred forty-four thousand, six hundred ninety-four".