642778911 has 36 divisors (see below), whose sum is σ = 1006568472. Its totient is φ = 394919712.

The previous prime is 642778883. The next prime is 642778919. The reversal of 642778911 is 119877246.

It is a happy number.

It is not a de Polignac number, because 642778911 - 2⁹ = 642778399 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642778919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 117540 + ... + 122886.

Almost surely, 2^642778911 is an apocalyptic number.

642778911 is a deficient number, since it is larger than the sum of its proper divisors (363789561).

642778911 is a wasteful number, since it uses less digits than its factorization.

642778911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5428 (or 5406 counting only the distinct ones).

The product of its digits is 169344, while the sum is 45.

The square root of 642778911 is about 25353.0848418886. The cubic root of 642778911 is about 863.0193630639.

The spelling of 642778911 in words is "six hundred forty-two million, seven hundred seventy-eight thousand, nine hundred eleven".