644978041 has 8 divisors (see below), whose sum is σ = 665470080. Its totient is φ = 624794352.

The previous prime is 644978023. The next prime is 644978057. The reversal of 644978041 is 140879446.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644978041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644978441) 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, 72835 + ... + 81208.

It is an arithmetic number, because the mean of its divisors is an integer number (83183760).

Almost surely, 2^644978041 is an apocalyptic number.

It is an amenable number.

644978041 is a deficient number, since it is larger than the sum of its proper divisors (20492039).

644978041 is a wasteful number, since it uses less digits than its factorization.

644978041 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154175.

The product of its (nonzero) digits is 193536, while the sum is 43.

The square root of 644978041 is about 25396.4178773307. The cubic root of 644978041 is about 864.0024545719.

The spelling of 644978041 in words is "six hundred forty-four million, nine hundred seventy-eight thousand, forty-one".