644451481 has 8 divisors (see below), whose sum is σ = 678831200. Its totient is φ = 610117920.

The previous prime is 644451473. The next prime is 644451499. The reversal of 644451481 is 184154446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644451481 - 2³ = 644451473 is a prime.

It is a super-2 number, since 2×644451481² = 830635422726186722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644451481.

It is not an unprimeable number, because it can be changed into a prime (644451461) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19261 + ... + 40741.

It is an arithmetic number, because the mean of its divisors is an integer number (84853900).

Almost surely, 2^644451481 is an apocalyptic number.

It is an amenable number.

644451481 is a deficient number, since it is larger than the sum of its proper divisors (34379719).

644451481 is a wasteful number, since it uses less digits than its factorization.

644451481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23079.

The product of its digits is 61440, while the sum is 37.

The square root of 644451481 is about 25386.0489442528. The cubic root of 644451481 is about 863.7672667223.

The spelling of 644451481 in words is "six hundred forty-four million, four hundred fifty-one thousand, four hundred eighty-one".