644661002 has 8 divisors (see below), whose sum is σ = 981424416. Its totient is φ = 317519532.

The previous prime is 644661001. The next prime is 644661007. The reversal of 644661002 is 200166446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (644661001) 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, 2405318 + ... + 2405585.

It is an arithmetic number, because the mean of its divisors is an integer number (122678052).

Almost surely, 2^644661002 is an apocalyptic number.

644661002 is a deficient number, since it is larger than the sum of its proper divisors (336763414).

644661002 is a wasteful number, since it uses less digits than its factorization.

644661002 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4810972.

The product of its (nonzero) digits is 6912, while the sum is 29.

The square root of 644661002 is about 25390.1753046331. The cubic root of 644661002 is about 863.8608645481.

The spelling of 644661002 in words is "six hundred forty-four million, six hundred sixty-one thousand, two".