644583781401 has 96 divisors (see below), whose sum is σ = 1060389446400. Its totient is φ = 348092349696.

The previous prime is 644583781393. The next prime is 644583781433. The reversal of 644583781401 is 104187385446.

It is not a de Polignac number, because 644583781401 - 2³ = 644583781393 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644583781481) by changing a digit.

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 95 ways as a sum of consecutive naturals, for example, 169759435 + ... + 169763231.

It is an arithmetic number, because the mean of its divisors is an integer number (11045723400).

Almost surely, 2^644583781401 is an apocalyptic number.

It is an amenable number.

644583781401 is a deficient number, since it is larger than the sum of its proper divisors (415805664999).

644583781401 is a wasteful number, since it uses less digits than its factorization.

644583781401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4316 (or 4283 counting only the distinct ones).

The product of its (nonzero) digits is 2580480, while the sum is 51.

The spelling of 644583781401 in words is "six hundred forty-four billion, five hundred eighty-three million, seven hundred eighty-one thousand, four hundred one".