644870654 has 4 divisors (see below), whose sum is σ = 967305984. Its totient is φ = 322435326.

The previous prime is 644870627. The next prime is 644870689. The reversal of 644870654 is 456078446.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161217662 + ... + 161217665.

It is an arithmetic number, because the mean of its divisors is an integer number (241826496).

Almost surely, 2^644870654 is an apocalyptic number.

644870654 is a deficient number, since it is larger than the sum of its proper divisors (322435330).

644870654 is a wasteful number, since it uses less digits than its factorization.

644870654 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322435329.

The product of its (nonzero) digits is 645120, while the sum is 44.

The square root of 644870654 is about 25394.3035738332. The cubic root of 644870654 is about 863.9545005975.

The spelling of 644870654 in words is "six hundred forty-four million, eight hundred seventy thousand, six hundred fifty-four".