642423456 has 72 divisors (see below), whose sum is σ = 1834376544. Its totient is φ = 213264000.

The previous prime is 642423451. The next prime is 642423479. The reversal of 642423456 is 654324246.

642423456 is a `hidden beast` number, since 642 + 4 + 2 + 3 + 4 + 5 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 642423456.

It is not an unprimeable number, because it can be changed into a prime (642423451) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 67845 + ... + 76731.

It is an arithmetic number, because the mean of its divisors is an integer number (25477452).

Almost surely, 2^642423456 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 642423456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (917188272).

642423456 is an abundant number, since it is smaller than the sum of its proper divisors (1191953088).

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

642423456 is a wasteful number, since it uses less digits than its factorization.

642423456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9154 (or 9143 counting only the distinct ones).

The product of its digits is 138240, while the sum is 36.

The square root of 642423456 is about 25346.0737787926. The cubic root of 642423456 is about 862.8602512727.

The spelling of 642423456 in words is "six hundred forty-two million, four hundred twenty-three thousand, four hundred fifty-six".