644520363 has 4 divisors (see below), whose sum is σ = 859360488. Its totient is φ = 429680240.

The previous prime is 644520361. The next prime is 644520403. The reversal of 644520363 is 363025446.

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

It is a cyclic number.

It is not a de Polignac number, because 644520363 - 2¹ = 644520361 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644520361) 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, 107420058 + ... + 107420063.

It is an arithmetic number, because the mean of its divisors is an integer number (214840122).

Almost surely, 2^644520363 is an apocalyptic number.

644520363 is a deficient number, since it is larger than the sum of its proper divisors (214840125).

644520363 is a wasteful number, since it uses less digits than its factorization.

644520363 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214840124.

The product of its (nonzero) digits is 51840, while the sum is 33.

The square root of 644520363 is about 25387.4055980520. The cubic root of 644520363 is about 863.7980401263.

The spelling of 644520363 in words is "six hundred forty-four million, five hundred twenty thousand, three hundred sixty-three".