77728331878 has 4 divisors (see below), whose sum is σ = 116592497820. Its totient is φ = 38864165938.

The previous prime is 77728331861. The next prime is 77728331881. The reversal of 77728331878 is 87813382777.

It is a semiprime because it is the product of two primes.

It is a super-2 number, since 2×77728331878² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19432082968 + ... + 19432082971.

It is an arithmetic number, because the mean of its divisors is an integer number (29148124455).

Almost surely, 2^77728331878 is an apocalyptic number.

77728331878 is a deficient number, since it is larger than the sum of its proper divisors (38864165942).

77728331878 is a wasteful number, since it uses less digits than its factorization.

77728331878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38864165941.

The product of its digits is 22127616, while the sum is 61.

The spelling of 77728331878 in words is "seventy-seven billion, seven hundred twenty-eight million, three hundred thirty-one thousand, eight hundred seventy-eight".