77556561 has 4 divisors (see below), whose sum is σ = 103408752. Its totient is φ = 51704372.

The previous prime is 77556547. The next prime is 77556599. The reversal of 77556561 is 16565577.

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 a cyclic number.

It is not a de Polignac number, because 77556561 - 2⁶ = 77556497 is a prime.

It is not an unprimeable number, because it can be changed into a prime (77556511) 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, 12926091 + ... + 12926096.

It is an arithmetic number, because the mean of its divisors is an integer number (25852188).

Almost surely, 2^77556561 is an apocalyptic number.

It is an amenable number.

77556561 is a deficient number, since it is larger than the sum of its proper divisors (25852191).

77556561 is a wasteful number, since it uses less digits than its factorization.

77556561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25852190.

The product of its digits is 220500, while the sum is 42.

The square root of 77556561 is about 8806.6202938471. The cubic root of 77556561 is about 426.4546436670.

The spelling of 77556561 in words is "seventy-seven million, five hundred fifty-six thousand, five hundred sixty-one".