644641122 has 32 divisors (see below), whose sum is σ = 1396878912. Its totient is φ = 197535744.

The previous prime is 644641099. The next prime is 644641159. The reversal of 644641122 is 221146446.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 644641122.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 69103 + ... + 77874.

It is an arithmetic number, because the mean of its divisors is an integer number (43652466).

Almost surely, 2^644641122 is an apocalyptic number.

644641122 is an abundant number, since it is smaller than the sum of its proper divisors (752237790).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644641122 is a wasteful number, since it uses less digits than its factorization.

644641122 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147042.

The product of its digits is 9216, while the sum is 30.

The square root of 644641122 is about 25389.7838116042. The cubic root of 644641122 is about 863.8519845680.

Adding to 644641122 its reverse (221146446), we get a palindrome (865787568).

The spelling of 644641122 in words is "six hundred forty-four million, six hundred forty-one thousand, one hundred twenty-two".