644157 has 12 divisors (see below), whose sum is σ = 979680. Its totient is φ = 406728.

The previous prime is 644153. The next prime is 644159. The reversal of 644157 is 751446.

644157 is a `hidden beast` number, since 644 + 15 + 7 = 666.

It is not a de Polignac number, because 644157 - 2² = 644153 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644157.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644153) 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 in 11 ways as a sum of consecutive naturals, for example, 1713 + ... + 2054.

It is an arithmetic number, because the mean of its divisors is an integer number (81640).

2⁶⁴⁴¹⁵⁷ is an apocalyptic number.

It is an amenable number.

644157 is a deficient number, since it is larger than the sum of its proper divisors (335523).

644157 is a wasteful number, since it uses less digits than its factorization.

644157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3792 (or 3789 counting only the distinct ones).

The product of its digits is 3360, while the sum is 27.

The square root of 644157 is about 802.5939197377. The cubic root of 644157 is about 86.3635681020.

The spelling of 644157 in words is "six hundred forty-four thousand, one hundred fifty-seven".