644198973 has 16 divisors (see below), whose sum is σ = 977757696. Its totient is φ = 373448240.

The previous prime is 644198923. The next prime is 644198981. The reversal of 644198973 is 379891446.

It is not a de Polignac number, because 644198973 - 2¹² = 644194877 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644198923) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 423615 + ... + 425132.

It is an arithmetic number, because the mean of its divisors is an integer number (61109856).

Almost surely, 2^644198973 is an apocalyptic number.

It is an amenable number.

644198973 is a deficient number, since it is larger than the sum of its proper divisors (333558723).

644198973 is a wasteful number, since it uses less digits than its factorization.

644198973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 848784.

The product of its digits is 1306368, while the sum is 51.

The square root of 644198973 is about 25381.0750954328. The cubic root of 644198973 is about 863.6544386591.

The spelling of 644198973 in words is "six hundred forty-four million, one hundred ninety-eight thousand, nine hundred seventy-three".