644022266 has 16 divisors (see below), whose sum is σ = 989604000. Its totient is φ = 314171088.

The previous prime is 644022263. The next prime is 644022283. The reversal of 644022266 is 662220446.

It is not an unprimeable number, because it can be changed into a prime (644022263) 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, 83960 + ... + 91308.

It is an arithmetic number, because the mean of its divisors is an integer number (61850250).

Almost surely, 2^644022266 is an apocalyptic number.

644022266 is a deficient number, since it is larger than the sum of its proper divisors (345581734).

644022266 is a wasteful number, since it uses less digits than its factorization.

644022266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8413.

The product of its (nonzero) digits is 27648, while the sum is 32.

The square root of 644022266 is about 25377.5937787648. The cubic root of 644022266 is about 863.5754631936.

The spelling of 644022266 in words is "six hundred forty-four million, twenty-two thousand, two hundred sixty-six".