644022641 has 8 divisors (see below), whose sum is σ = 654186624. Its totient is φ = 633934080.

The previous prime is 644022581. The next prime is 644022649. The reversal of 644022641 is 146220446.

It is a happy number.

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 644022641 - 2¹⁸ = 643760497 is a prime.

It is a super-2 number, since 2×644022641² = 829530324241229762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644022649) 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, 1520 + ... + 35921.

It is an arithmetic number, because the mean of its divisors is an integer number (81773328).

Almost surely, 2^644022641 is an apocalyptic number.

It is an amenable number.

644022641 is a deficient number, since it is larger than the sum of its proper divisors (10163983).

644022641 is a wasteful number, since it uses less digits than its factorization.

644022641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37711.

The product of its (nonzero) digits is 9216, while the sum is 29.

The square root of 644022641 is about 25377.6011671710. The cubic root of 644022641 is about 863.5756308072.

The spelling of 644022641 in words is "six hundred forty-four million, twenty-two thousand, six hundred forty-one".