77778488991 has 8 divisors (see below), whose sum is σ = 118519602304. Its totient is φ = 44444850840.

The previous prime is 77778488947. The next prime is 77778488999. The reversal of 77778488991 is 19988487777.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 77778488991 - 2¹⁸ = 77778226847 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77778488999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1851868765 + ... + 1851868806.

It is an arithmetic number, because the mean of its divisors is an integer number (14814950288).

Almost surely, 2^77778488991 is an apocalyptic number.

77778488991 is a deficient number, since it is larger than the sum of its proper divisors (40741113313).

77778488991 is a wasteful number, since it uses less digits than its factorization.

77778488991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3703737581.

The product of its digits is 398297088, while the sum is 75.

The spelling of 77778488991 in words is "seventy-seven billion, seven hundred seventy-eight million, four hundred eighty-eight thousand, nine hundred ninety-one".