642189755 has 4 divisors (see below), whose sum is σ = 770627712. Its totient is φ = 513751800.

The previous prime is 642189749. The next prime is 642189767. The reversal of 642189755 is 557981246.

It is a happy number.

642189755 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 not a de Polignac number, because 642189755 - 2²² = 637995451 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64218971 + ... + 64218980.

It is an arithmetic number, because the mean of its divisors is an integer number (192656928).

Almost surely, 2^642189755 is an apocalyptic number.

642189755 is a deficient number, since it is larger than the sum of its proper divisors (128437957).

642189755 is a wasteful number, since it uses less digits than its factorization.

642189755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128437956.

The product of its digits is 604800, while the sum is 47.

The square root of 642189755 is about 25341.4631582314. The cubic root of 642189755 is about 862.7556080612.

The spelling of 642189755 in words is "six hundred forty-two million, one hundred eighty-nine thousand, seven hundred fifty-five".