644692231 has 8 divisors (see below), whose sum is σ = 673192800. Its totient is φ = 616230912.

The previous prime is 644692199. The next prime is 644692261. The reversal of 644692231 is 132296446.

It is a happy number.

644692231 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 644692231 - 2⁵ = 644692199 is a prime.

It is a super-2 number, since 2×644692231² = 831256145423514722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644692261) 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, 26695 + ... + 44743.

It is an arithmetic number, because the mean of its divisors is an integer number (84149100).

Almost surely, 2^644692231 is an apocalyptic number.

644692231 is a deficient number, since it is larger than the sum of its proper divisors (28500569).

644692231 is a wasteful number, since it uses less digits than its factorization.

644692231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19625.

The product of its digits is 62208, while the sum is 37.

The square root of 644692231 is about 25390.7902791544. The cubic root of 644692231 is about 863.8748135203.

The spelling of 644692231 in words is "six hundred forty-four million, six hundred ninety-two thousand, two hundred thirty-one".