11996995721 has 4 divisors (see below), whose sum is σ = 12193667844. Its totient is φ = 11800323600.

The previous prime is 11996995709. The next prime is 11996995723. The reversal of 11996995721 is 12759969911.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12759969911 = 13 ⋅981536147.

It can be written as a sum of positive squares in 2 ways, for example, as 4404313225 + 7592682496 = 66365^2 + 87136^2 .

It is a cyclic number.

It is not a de Polignac number, because 11996995721 - 2²² = 11992801417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11996995723) 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, 98335970 + ... + 98336091.

It is an arithmetic number, because the mean of its divisors is an integer number (3048416961).

Almost surely, 2^11996995721 is an apocalyptic number.

It is an amenable number.

11996995721 is a deficient number, since it is larger than the sum of its proper divisors (196672123).

11996995721 is an equidigital number, since it uses as much as digits as its factorization.

11996995721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196672122.

The product of its digits is 2755620, while the sum is 59.

The spelling of 11996995721 in words is "eleven billion, nine hundred ninety-six million, nine hundred ninety-five thousand, seven hundred twenty-one".