81790780771 has 4 divisors (see below), whose sum is σ = 93475178032. Its totient is φ = 70106383512.

The previous prime is 81790780763. The next prime is 81790780801. The reversal of 81790780771 is 17708709718.

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

It is a cyclic number.

It is not a de Polignac number, because 81790780771 - 2³ = 81790780763 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81790780871) 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, 5842198620 + ... + 5842198633.

It is an arithmetic number, because the mean of its divisors is an integer number (23368794508).

Almost surely, 2^81790780771 is an apocalyptic number.

81790780771 is a deficient number, since it is larger than the sum of its proper divisors (11684397261).

81790780771 is a wasteful number, since it uses less digits than its factorization.

81790780771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11684397260.

The product of its (nonzero) digits is 1382976, while the sum is 55.

The spelling of 81790780771 in words is "eighty-one billion, seven hundred ninety million, seven hundred eighty thousand, seven hundred seventy-one".