661777777166 has 32 divisors (see below), whose sum is σ = 1090975236480. Its totient is φ = 298573711200.

The previous prime is 661777777151. The next prime is 661777777211.

It is a happy number.

661777777166 is nontrivially palindromic in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 661777777096 and 661777777105.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1975145 + ... + 2285771.

It is an arithmetic number, because the mean of its divisors is an integer number (34092976140).

Almost surely, 2^661777777166 is an apocalyptic number.

661777777166 is a deficient number, since it is larger than the sum of its proper divisors (429197459314).

661777777166 is a wasteful number, since it uses less digits than its factorization.

661777777166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 311360.

The product of its digits is 152473104, while the sum is 68.

The spelling of 661777777166 in words is "six hundred sixty-one billion, seven hundred seventy-seven million, seven hundred seventy-seven thousand, one hundred sixty-six".