644231087 has 4 divisors (see below), whose sum is σ = 661642776. Its totient is φ = 626819400.

The previous prime is 644231083. The next prime is 644231123. The reversal of 644231087 is 780132446.

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 644231087 - 2² = 644231083 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644231083) 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, 8705789 + ... + 8705862.

It is an arithmetic number, because the mean of its divisors is an integer number (165410694).

Almost surely, 2^644231087 is an apocalyptic number.

644231087 is a deficient number, since it is larger than the sum of its proper divisors (17411689).

644231087 is a wasteful number, since it uses less digits than its factorization.

644231087 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17411688.

The product of its (nonzero) digits is 32256, while the sum is 35.

The square root of 644231087 is about 25381.7077242647. The cubic root of 644231087 is about 863.6687897829.

The spelling of 644231087 in words is "six hundred forty-four million, two hundred thirty-one thousand, eighty-seven".