644117730 has 16 divisors (see below), whose sum is σ = 1545882624. Its totient is φ = 171764720.

The previous prime is 644117713. The next prime is 644117779. The reversal of 644117730 is 37711446.

644117730 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 644117691 and 644117700.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10735266 + ... + 10735325.

It is an arithmetic number, because the mean of its divisors is an integer number (96617664).

Almost surely, 2^644117730 is an apocalyptic number.

644117730 is an abundant number, since it is smaller than the sum of its proper divisors (901764894).

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

644117730 is a wasteful number, since it uses less digits than its factorization.

644117730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21470601.

The product of its (nonzero) digits is 14112, while the sum is 33.

The square root of 644117730 is about 25379.4745808498. The cubic root of 644117730 is about 863.6181306081.

The spelling of 644117730 in words is "six hundred forty-four million, one hundred seventeen thousand, seven hundred thirty".