644061187 has 8 divisors (see below), whose sum is σ = 802985472. Its totient is φ = 501865800.

The previous prime is 644061161. The next prime is 644061193. The reversal of 644061187 is 781160446.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 644061187 - 2⁷ = 644061059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644001187) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4182139 + ... + 4182292.

It is an arithmetic number, because the mean of its divisors is an integer number (100373184).

Almost surely, 2^644061187 is an apocalyptic number.

644061187 is a deficient number, since it is larger than the sum of its proper divisors (158924285).

644061187 is a wasteful number, since it uses less digits than its factorization.

644061187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8364449.

The product of its (nonzero) digits is 32256, while the sum is 37.

The square root of 644061187 is about 25378.3606050509. The cubic root of 644061187 is about 863.5928593538.

The spelling of 644061187 in words is "six hundred forty-four million, sixty-one thousand, one hundred eighty-seven".