642745778 has 4 divisors (see below), whose sum is σ = 964118670. Its totient is φ = 321372888.

The previous prime is 642745769. The next prime is 642745783. The reversal of 642745778 is 877547246.

642745778 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 can be written as a sum of positive squares in only one way, i.e., 635897089 + 6848689 = 25217^2 + 2617^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160686443 + ... + 160686446.

Almost surely, 2^642745778 is an apocalyptic number.

642745778 is a deficient number, since it is larger than the sum of its proper divisors (321372892).

642745778 is a wasteful number, since it uses less digits than its factorization.

642745778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321372891.

The product of its digits is 2634240, while the sum is 50.

The square root of 642745778 is about 25352.4314021358. The cubic root of 642745778 is about 863.0045342680.

The spelling of 642745778 in words is "six hundred forty-two million, seven hundred forty-five thousand, seven hundred seventy-eight".