77764561 has 4 divisors (see below), whose sum is σ = 88873792. Its totient is φ = 66655332.

The previous prime is 77764559. The next prime is 77764571. The reversal of 77764561 is 16546777.

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 77764561 - 2¹ = 77764559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (77764571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5554605 + ... + 5554618.

It is an arithmetic number, because the mean of its divisors is an integer number (22218448).

Almost surely, 2^77764561 is an apocalyptic number.

It is an amenable number.

77764561 is a deficient number, since it is larger than the sum of its proper divisors (11109231).

77764561 is a wasteful number, since it uses less digits than its factorization.

77764561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11109230.

The product of its digits is 246960, while the sum is 43.

The square root of 77764561 is about 8818.4216841791. The cubic root of 77764561 is about 426.8355415353.

The spelling of 77764561 in words is "seventy-seven million, seven hundred sixty-four thousand, five hundred sixty-one".