644420427 has 32 divisors (see below), whose sum is σ = 996602880. Its totient is φ = 362793600.

The previous prime is 644420423. The next prime is 644420443. The reversal of 644420427 is 724024446.

It is not a de Polignac number, because 644420427 - 2² = 644420423 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644420423) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 494677 + ... + 495977.

It is an arithmetic number, because the mean of its divisors is an integer number (31143840).

Almost surely, 2^644420427 is an apocalyptic number.

644420427 is a deficient number, since it is larger than the sum of its proper divisors (352182453).

644420427 is a wasteful number, since it uses less digits than its factorization.

644420427 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1643.

The product of its (nonzero) digits is 43008, while the sum is 33.

The square root of 644420427 is about 25385.4373017287. The cubic root of 644420427 is about 863.7533924637.

The spelling of 644420427 in words is "six hundred forty-four million, four hundred twenty thousand, four hundred twenty-seven".