77755553661 has 4 divisors (see below), whose sum is σ = 103674071552. Its totient is φ = 51837035772.

The previous prime is 77755553657. The next prime is 77755553671. The reversal of 77755553661 is 16635555777.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 77755553661 - 2² = 77755553657 is a prime.

It is a super-2 number, since 2×77755553661² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77755553651) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12959258941 + ... + 12959258946.

It is an arithmetic number, because the mean of its divisors is an integer number (25918517888).

Almost surely, 2^77755553661 is an apocalyptic number.

It is an amenable number.

77755553661 is a deficient number, since it is larger than the sum of its proper divisors (25918517891).

77755553661 is a wasteful number, since it uses less digits than its factorization.

77755553661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25918517890.

The product of its digits is 23152500, while the sum is 57.

The spelling of 77755553661 in words is "seventy-seven billion, seven hundred fifty-five million, five hundred fifty-three thousand, six hundred sixty-one".