668778823 has 2 divisors, whose sum is σ = 668778824. Its totient is φ = 668778822.

The previous prime is 668778809. The next prime is 668778833. The reversal of 668778823 is 328877866.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 668778823 - 2⁹ = 668778311 is a prime.

It is a super-2 number, since 2×668778823² = 894530228186530658, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668778833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334389411 + 334389412.

It is an arithmetic number, because the mean of its divisors is an integer number (334389412).

Almost surely, 2^668778823 is an apocalyptic number.

668778823 is a deficient number, since it is larger than the sum of its proper divisors (1).

668778823 is an equidigital number, since it uses as much as digits as its factorization.

668778823 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5419008, while the sum is 55.

The square root of 668778823 is about 25860.7583608834. The cubic root of 668778823 is about 874.5020613980.

The spelling of 668778823 in words is "six hundred sixty-eight million, seven hundred seventy-eight thousand, eight hundred twenty-three".