642638023 has 4 divisors (see below), whose sum is σ = 642976920. Its totient is φ = 642299128.

The previous prime is 642638011. The next prime is 642638033. The reversal of 642638023 is 320836246.

642638023 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 642638023 - 2²¹ = 640540871 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 642638023.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642638033) 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, 166588 + ... + 170401.

It is an arithmetic number, because the mean of its divisors is an integer number (160744230).

Almost surely, 2^642638023 is an apocalyptic number.

642638023 is a deficient number, since it is larger than the sum of its proper divisors (338897).

642638023 is a wasteful number, since it uses less digits than its factorization.

642638023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338896.

The product of its (nonzero) digits is 41472, while the sum is 34.

The square root of 642638023 is about 25350.3061717211. The cubic root of 642638023 is about 862.9563045978.

The spelling of 642638023 in words is "six hundred forty-two million, six hundred thirty-eight thousand, twenty-three".