644266740 has 48 divisors (see below), whose sum is σ = 1942714368. Its totient is φ = 158588544.

The previous prime is 644266739. The next prime is 644266759. The reversal of 644266740 is 47662446.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 412212 + ... + 413771.

It is an arithmetic number, because the mean of its divisors is an integer number (40473216).

Almost surely, 2^644266740 is an apocalyptic number.

644266740 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644266740 is an abundant number, since it is smaller than the sum of its proper divisors (1298447628).

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

644266740 is a wasteful number, since it uses less digits than its factorization.

644266740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 826008 (or 826006 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 39.

The square root of 644266740 is about 25382.4100510570. The cubic root of 644266740 is about 863.6847218586.

The spelling of 644266740 in words is "six hundred forty-four million, two hundred sixty-six thousand, seven hundred forty".