644154650 has 24 divisors (see below), whose sum is σ = 1268607420. Its totient is φ = 242504960.

The previous prime is 644154631. The next prime is 644154653. The reversal of 644154650 is 56451446.

It can be written as a sum of positive squares in 6 ways, for example, as 496264729 + 147889921 = 22277^2 + 12161^2 .

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 644154650.

It is not an unprimeable number, because it can be changed into a prime (644154653) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 378065 + ... + 379764.

Almost surely, 2^644154650 is an apocalyptic number.

644154650 is a deficient number, since it is larger than the sum of its proper divisors (624452770).

644154650 is a wasteful number, since it uses less digits than its factorization.

644154650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 757858 (or 757853 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 35.

The square root of 644154650 is about 25380.2019298508. The cubic root of 644154650 is about 863.6346307864.

The spelling of 644154650 in words is "six hundred forty-four million, one hundred fifty-four thousand, six hundred fifty".