644967506 has 16 divisors (see below), whose sum is σ = 975693600. Its totient is φ = 319742688.

The previous prime is 644967503. The next prime is 644967523. The reversal of 644967506 is 605769446.

It is not an unprimeable number, because it can be changed into a prime (644967503) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 397565 + ... + 399183.

It is an arithmetic number, because the mean of its divisors is an integer number (60980850).

Almost surely, 2^644967506 is an apocalyptic number.

644967506 is a deficient number, since it is larger than the sum of its proper divisors (330726094).

644967506 is a wasteful number, since it uses less digits than its factorization.

644967506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3193.

The product of its (nonzero) digits is 1088640, while the sum is 47.

The square root of 644967506 is about 25396.2104653431. The cubic root of 644967506 is about 863.9977503728.

The spelling of 644967506 in words is "six hundred forty-four million, nine hundred sixty-seven thousand, five hundred six".