668878551 has 24 divisors (see below), whose sum is σ = 1079704080. Its totient is φ = 395491200.

The previous prime is 668878547. The next prime is 668878577. The reversal of 668878551 is 155878866.

668878551 is a `hidden beast` number, since 6 + 6 + 8 + 87 + 8 + 551 = 666.

It is not a de Polignac number, because 668878551 - 2² = 668878547 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668878051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 78336 + ... + 86453.

It is an arithmetic number, because the mean of its divisors is an integer number (44987670).

Almost surely, 2^668878551 is an apocalyptic number.

668878551 is a deficient number, since it is larger than the sum of its proper divisors (410825529).

668878551 is a wasteful number, since it uses less digits than its factorization.

668878551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164847 (or 164844 counting only the distinct ones).

The product of its digits is 3225600, while the sum is 54.

The square root of 668878551 is about 25862.6864613868. The cubic root of 668878551 is about 874.5455276900.

The spelling of 668878551 in words is "six hundred sixty-eight million, eight hundred seventy-eight thousand, five hundred fifty-one".