642640368 has 80 divisors (see below), whose sum is σ = 1700585600. Its totient is φ = 209053440.

The previous prime is 642640367. The next prime is 642640391. The reversal of 642640368 is 863046246.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642640367) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 406203 + ... + 407781.

It is an arithmetic number, because the mean of its divisors is an integer number (21257320).

Almost surely, 2^642640368 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 642640368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (850292800).

642640368 is an abundant number, since it is smaller than the sum of its proper divisors (1057945232).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

642640368 is a wasteful number, since it uses less digits than its factorization.

642640368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1790 (or 1784 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 39.

The square root of 642640368 is about 25350.3524235858. The cubic root of 642640368 is about 862.9573542452.

The spelling of 642640368 in words is "six hundred forty-two million, six hundred forty thousand, three hundred sixty-eight".