666777778390 has 16 divisors (see below), whose sum is σ = 1202280080832. Its totient is φ = 266248871424.

The previous prime is 666777778379. The next prime is 666777778411. The reversal of 666777778390 is 93877777666.

It is a super-3 number, since 3×666777778390³ (a number of 36 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57773934 + ... + 57785473.

It is an arithmetic number, because the mean of its divisors is an integer number (75142505052).

Almost surely, 2^666777778390 is an apocalyptic number.

666777778390 is a deficient number, since it is larger than the sum of its proper divisors (535502302442).

666777778390 is a wasteful number, since it uses less digits than its factorization.

666777778390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115559991.

The product of its (nonzero) digits is 784147392, while the sum is 73.

The spelling of 666777778390 in words is "six hundred sixty-six billion, seven hundred seventy-seven million, seven hundred seventy-eight thousand, three hundred ninety".