11720723891 has 4 divisors (see below), whose sum is σ = 11720984400. Its totient is φ = 11720463384.

The previous prime is 11720723881. The next prime is 11720723909. The reversal of 11720723891 is 19832702711.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19832702711 = 71 ⋅279333841.

It is a cyclic number.

It is not a de Polignac number, because 11720723891 - 2¹⁴ = 11720707507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11720723881) 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, 43511 + ... + 159168.

It is an arithmetic number, because the mean of its divisors is an integer number (2930246100).

Almost surely, 2^11720723891 is an apocalyptic number.

11720723891 is a deficient number, since it is larger than the sum of its proper divisors (260509).

11720723891 is an equidigital number, since it uses as much as digits as its factorization.

11720723891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260508.

The product of its (nonzero) digits is 42336, while the sum is 41.

The spelling of 11720723891 in words is "eleven billion, seven hundred twenty million, seven hundred twenty-three thousand, eight hundred ninety-one".