77491919561 has 4 divisors (see below), whose sum is σ = 88562193792. Its totient is φ = 66421645332.

The previous prime is 77491919537. The next prime is 77491919627. The reversal of 77491919561 is 16591919477.

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 de Polignac number, because none of the positive numbers 2^k-77491919561 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 77491919561.

It is not an unprimeable number, because it can be changed into a prime (77491919761) 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, 5535137105 + ... + 5535137118.

It is an arithmetic number, because the mean of its divisors is an integer number (22140548448).

Almost surely, 2^77491919561 is an apocalyptic number.

It is an amenable number.

77491919561 is a deficient number, since it is larger than the sum of its proper divisors (11070274231).

77491919561 is a wasteful number, since it uses less digits than its factorization.

77491919561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11070274230.

The product of its digits is 4286520, while the sum is 59.

The spelling of 77491919561 in words is "seventy-seven billion, four hundred ninety-one million, nine hundred nineteen thousand, five hundred sixty-one".