644230061 has 4 divisors (see below), whose sum is σ = 645274812. Its totient is φ = 643185312.

The previous prime is 644230057. The next prime is 644230109. The reversal of 644230061 is 160032446.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 34880836 + 609349225 = 5906^2 + 24685^2 .

It is a cyclic number.

It is not a de Polignac number, because 644230061 - 2² = 644230057 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 644230061.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644230021) 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, 521450 + ... + 522683.

It is an arithmetic number, because the mean of its divisors is an integer number (161318703).

Almost surely, 2^644230061 is an apocalyptic number.

It is an amenable number.

644230061 is a deficient number, since it is larger than the sum of its proper divisors (1044751).

644230061 is a wasteful number, since it uses less digits than its factorization.

644230061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1044750.

The product of its (nonzero) digits is 3456, while the sum is 26.

The square root of 644230061 is about 25381.6875128507. The cubic root of 644230061 is about 863.6683312908.

The spelling of 644230061 in words is "six hundred forty-four million, two hundred thirty thousand, sixty-one".