642382021 has 2 divisors, whose sum is σ = 642382022. Its totient is φ = 642382020.

The previous prime is 642381991. The next prime is 642382067. The reversal of 642382021 is 120283246.

642382021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 642369025 + 12996 = 25345^2 + 114^2 .

It is a cyclic number.

It is not a de Polignac number, because 642382021 - 2⁷ = 642381893 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642382121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321191010 + 321191011.

It is an arithmetic number, because the mean of its divisors is an integer number (321191011).

Almost surely, 2^642382021 is an apocalyptic number.

It is an amenable number.

642382021 is a deficient number, since it is larger than the sum of its proper divisors (1).

642382021 is an equidigital number, since it uses as much as digits as its factorization.

642382021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 642382021 is about 25345.2563806326. The cubic root of 642382021 is about 862.8416999662.

The spelling of 642382021 in words is "six hundred forty-two million, three hundred eighty-two thousand, twenty-one".