644561061 has 4 divisors (see below), whose sum is σ = 859414752. Its totient is φ = 429707372.

The previous prime is 644561059. The next prime is 644561077. The reversal of 644561061 is 160165446.

It is a happy number.

644561061 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 644561061 - 2¹ = 644561059 is a prime.

It is a super-2 number, since 2×644561061² = 830917922714891442, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644521061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107426841 + ... + 107426846.

It is an arithmetic number, because the mean of its divisors is an integer number (214853688).

Almost surely, 2^644561061 is an apocalyptic number.

It is an amenable number.

644561061 is a deficient number, since it is larger than the sum of its proper divisors (214853691).

644561061 is a wasteful number, since it uses less digits than its factorization.

644561061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214853690.

The product of its (nonzero) digits is 17280, while the sum is 33.

The square root of 644561061 is about 25388.2071245687. The cubic root of 644561061 is about 863.8162211462.

The spelling of 644561061 in words is "six hundred forty-four million, five hundred sixty-one thousand, sixty-one".