77666661 has 16 divisors (see below), whose sum is σ = 121118400. Its totient is φ = 49052304.

The previous prime is 77666657. The next prime is 77666681. The reversal of 77666661 is 16666677.

It is not a de Polignac number, because 77666661 - 2² = 77666657 is a prime.

It is a super-2 number, since 2×77666661² = 12064220461777842, which contains 22 as substring.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77666621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 75186 + ... + 76211.

It is an arithmetic number, because the mean of its divisors is an integer number (7569900).

Almost surely, 2^77666661 is an apocalyptic number.

It is an amenable number.

77666661 is a deficient number, since it is larger than the sum of its proper divisors (43451739).

77666661 is a wasteful number, since it uses less digits than its factorization.

77666661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151425 (or 151419 counting only the distinct ones).

The product of its digits is 381024, while the sum is 45.

The square root of 77666661 is about 8812.8690561020. The cubic root of 77666661 is about 426.6563478814.

The spelling of 77666661 in words is "seventy-seven million, six hundred sixty-six thousand, six hundred sixty-one".