644557147 has 4 divisors (see below), whose sum is σ = 694138480. Its totient is φ = 594975816.

The previous prime is 644557127. The next prime is 644557153. The reversal of 644557147 is 741755446.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 644557147 - 2⁷ = 644557019 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644557127) 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, 24790647 + ... + 24790672.

It is an arithmetic number, because the mean of its divisors is an integer number (173534620).

Almost surely, 2^644557147 is an apocalyptic number.

644557147 is a deficient number, since it is larger than the sum of its proper divisors (49581333).

644557147 is a wasteful number, since it uses less digits than its factorization.

644557147 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49581332.

The product of its digits is 470400, while the sum is 43.

The square root of 644557147 is about 25388.1300414190. The cubic root of 644557147 is about 863.8144726780.

The spelling of 644557147 in words is "six hundred forty-four million, five hundred fifty-seven thousand, one hundred forty-seven".