642357621 has 28 divisors (see below), whose sum is σ = 965158348. Its totient is φ = 427322304.

The previous prime is 642357613. The next prime is 642357641. The reversal of 642357621 is 126753246.

642357621 is a `hidden beast` number, since 6 + 4 + 23 + 5 + 7 + 621 = 666.

642357621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 339075396 + 303282225 = 18414^2 + 17415^2 .

It is not a de Polignac number, because 642357621 - 2³ = 642357613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642357641) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 621321 + ... + 622353.

It is an arithmetic number, because the mean of its divisors is an integer number (34469941).

Almost surely, 2^642357621 is an apocalyptic number.

It is an amenable number.

642357621 is a deficient number, since it is larger than the sum of its proper divisors (322800727).

642357621 is an equidigital number, since it uses as much as digits as its factorization.

642357621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1904 (or 1889 counting only the distinct ones).

The product of its digits is 60480, while the sum is 36.

The square root of 642357621 is about 25344.7750236612. The cubic root of 642357621 is about 862.8307752084.

The spelling of 642357621 in words is "six hundred forty-two million, three hundred fifty-seven thousand, six hundred twenty-one".