78771556681 has 4 divisors (see below), whose sum is σ = 80603453392. Its totient is φ = 76939659972.

The previous prime is 78771556673. The next prime is 78771556691. The reversal of 78771556681 is 18665517787.

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 78771556681 - 2³ = 78771556673 is a prime.

It is a super-2 number, since 2×78771556681² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78771556621) 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, 915948291 + ... + 915948376.

It is an arithmetic number, because the mean of its divisors is an integer number (20150863348).

Almost surely, 2^78771556681 is an apocalyptic number.

It is an amenable number.

78771556681 is a deficient number, since it is larger than the sum of its proper divisors (1831896711).

78771556681 is a wasteful number, since it uses less digits than its factorization.

78771556681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1831896710.

The product of its digits is 19756800, while the sum is 61.

The spelling of 78771556681 in words is "seventy-eight billion, seven hundred seventy-one million, five hundred fifty-six thousand, six hundred eighty-one".