668879551 has 2 divisors, whose sum is σ = 668879552. Its totient is φ = 668879550.

The previous prime is 668879543. The next prime is 668879573. The reversal of 668879551 is 155978866.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 668879551 - 2³ = 668879543 is a prime.

It is a nialpdrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 668879492 and 668879501.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668879531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334439775 + 334439776.

It is an arithmetic number, because the mean of its divisors is an integer number (334439776).

Almost surely, 2^668879551 is an apocalyptic number.

668879551 is a deficient number, since it is larger than the sum of its proper divisors (1).

668879551 is an equidigital number, since it uses as much as digits as its factorization.

668879551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3628800, while the sum is 55.

The square root of 668879551 is about 25862.7057942513. The cubic root of 668879551 is about 874.5459635166.

The spelling of 668879551 in words is "six hundred sixty-eight million, eight hundred seventy-nine thousand, five hundred fifty-one".