644511955 has 8 divisors (see below), whose sum is σ = 774448704. Its totient is φ = 514920000.

The previous prime is 644511913. The next prime is 644511971. The reversal of 644511955 is 559115446.

It is a happy number.

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

It is not a de Polignac number, because 644511955 - 2⁷ = 644511827 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 82066 + ... + 89575.

It is an arithmetic number, because the mean of its divisors is an integer number (96806088).

Almost surely, 2^644511955 is an apocalyptic number.

644511955 is a deficient number, since it is larger than the sum of its proper divisors (129936749).

644511955 is a wasteful number, since it uses less digits than its factorization.

644511955 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172397.

The product of its digits is 108000, while the sum is 40.

The square root of 644511955 is about 25387.2400035924. The cubic root of 644511955 is about 863.7942839245.

The spelling of 644511955 in words is "six hundred forty-four million, five hundred eleven thousand, nine hundred fifty-five".