644141840 has 40 divisors (see below), whose sum is σ = 1507576128. Its totient is φ = 255945600.

The previous prime is 644141833. The next prime is 644141851. The reversal of 644141840 is 48141446.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 644141797 and 644141806.

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, 14582 + ... + 38741.

Almost surely, 2^644141840 is an apocalyptic number.

It is an amenable number.

644141840 is an abundant number, since it is smaller than the sum of its proper divisors (863434288).

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

644141840 is a wasteful number, since it uses less digits than its factorization.

644141840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53487 (or 53481 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 32.

The square root of 644141840 is about 25379.9495665378. The cubic root of 644141840 is about 863.6289058501.

The spelling of 644141840 in words is "six hundred forty-four million, one hundred forty-one thousand, eight hundred forty".