81953765779 has 4 divisors (see below), whose sum is σ = 81954764640. Its totient is φ = 81952766920.

The previous prime is 81953765759. The next prime is 81953765837. The reversal of 81953765779 is 97756735918.

It is a happy number.

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 81953765779 - 2²¹ = 81951668627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81953765759) 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, 364144 + ... + 544525.

It is an arithmetic number, because the mean of its divisors is an integer number (20488691160).

Almost surely, 2^81953765779 is an apocalyptic number.

81953765779 is a deficient number, since it is larger than the sum of its proper divisors (998861).

81953765779 is an equidigital number, since it uses as much as digits as its factorization.

81953765779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 998860.

The product of its digits is 100018800, while the sum is 67.

The spelling of 81953765779 in words is "eighty-one billion, nine hundred fifty-three million, seven hundred sixty-five thousand, seven hundred seventy-nine".