642544621 has 2 divisors, whose sum is σ = 642544622. Its totient is φ = 642544620.

The previous prime is 642544601. The next prime is 642544687. The reversal of 642544621 is 126445246.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 621255625 + 21288996 = 24925^2 + 4614^2 .

It is a cyclic number.

It is not a de Polignac number, because 642544621 - 2⁵ = 642544589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642544601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321272310 + 321272311.

It is an arithmetic number, because the mean of its divisors is an integer number (321272311).

Almost surely, 2^642544621 is an apocalyptic number.

It is an amenable number.

642544621 is a deficient number, since it is larger than the sum of its proper divisors (1).

642544621 is an equidigital number, since it uses as much as digits as its factorization.

642544621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 46080, while the sum is 34.

The square root of 642544621 is about 25348.4638785075. The cubic root of 642544621 is about 862.9144947727.

Adding to 642544621 its reverse (126445246), we get a palindrome (768989867).

The spelling of 642544621 in words is "six hundred forty-two million, five hundred forty-four thousand, six hundred twenty-one".