644142650 has 48 divisors (see below), whose sum is σ = 1217433240. Its totient is φ = 253536000.

The previous prime is 644142647. The next prime is 644142671. The reversal of 644142650 is 56241446.

644142650 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 12 ways, for example, as 182709289 + 461433361 = 13517^2 + 21481^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1156172 + ... + 1156728.

Almost surely, 2^644142650 is an apocalyptic number.

644142650 is a deficient number, since it is larger than the sum of its proper divisors (573290590).

644142650 is a wasteful number, since it uses less digits than its factorization.

644142650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 899 (or 894 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 32.

The square root of 644142650 is about 25379.9655240113. The cubic root of 644142650 is about 863.6292678507.

The spelling of 644142650 in words is "six hundred forty-four million, one hundred forty-two thousand, six hundred fifty".