644221442 has 16 divisors (see below), whose sum is σ = 989736000. Its totient is φ = 314323632.

The previous prime is 644221439. The next prime is 644221453. The reversal of 644221442 is 244122446.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 109184 + ... + 114932.

It is an arithmetic number, because the mean of its divisors is an integer number (61858500).

Almost surely, 2^644221442 is an apocalyptic number.

644221442 is a deficient number, since it is larger than the sum of its proper divisors (345514558).

644221442 is a wasteful number, since it uses less digits than its factorization.

644221442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7097.

The product of its digits is 12288, while the sum is 29.

The square root of 644221442 is about 25381.5177245176. The cubic root of 644221442 is about 863.6644796696.

Adding to 644221442 its reverse (244122446), we get a palindrome (888343888).

The spelling of 644221442 in words is "six hundred forty-four million, two hundred twenty-one thousand, four hundred forty-two".