644726760 has 32 divisors (see below), whose sum is σ = 1934180640. Its totient is φ = 171927104.

The previous prime is 644726759. The next prime is 644726773. The reversal of 644726760 is 67627446.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2686242 + ... + 2686481.

It is an arithmetic number, because the mean of its divisors is an integer number (60443145).

Almost surely, 2^644726760 is an apocalyptic number.

644726760 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644726760 is an abundant number, since it is smaller than the sum of its proper divisors (1289453880).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644726760 is a wasteful number, since it uses less digits than its factorization.

644726760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5372737 (or 5372733 counting only the distinct ones).

The product of its (nonzero) digits is 338688, while the sum is 42.

The square root of 644726760 is about 25391.4702213164. The cubic root of 644726760 is about 863.8902359702.

The spelling of 644726760 in words is "six hundred forty-four million, seven hundred twenty-six thousand, seven hundred sixty".