644022601 has 4 divisors (see below), whose sum is σ = 651258900. Its totient is φ = 636786304.

The previous prime is 644022581. The next prime is 644022649. The reversal of 644022601 is 106220446.

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 129413376 + 514609225 = 11376^2 + 22685^2 .

It is a cyclic number.

It is not a de Polignac number, because 644022601 - 2⁷ = 644022473 is a prime.

It is a super-2 number, since 2×644022601² = 829530221197610402, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644022661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3618016 + ... + 3618193.

It is an arithmetic number, because the mean of its divisors is an integer number (162814725).

Almost surely, 2^644022601 is an apocalyptic number.

It is an amenable number.

644022601 is a deficient number, since it is larger than the sum of its proper divisors (7236299).

644022601 is an equidigital number, since it uses as much as digits as its factorization.

644022601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7236298.

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 644022601 is about 25377.6003790745. The cubic root of 644022601 is about 863.5756129284.

The spelling of 644022601 in words is "six hundred forty-four million, twenty-two thousand, six hundred one".