11722640721 has 16 divisors (see below), whose sum is σ = 17083741440. Its totient is φ = 7091035920.

The previous prime is 11722640603. The next prime is 11722640801. The reversal of 11722640721 is 12704622711.

It is not a de Polignac number, because 11722640721 - 2⁷ = 11722640593 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (11722644721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 322351 + ... + 356868.

It is an arithmetic number, because the mean of its divisors is an integer number (1067733840).

Almost surely, 2^11722640721 is an apocalyptic number.

11722640721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11722640721 is a deficient number, since it is larger than the sum of its proper divisors (5361100719).

11722640721 is a wasteful number, since it uses less digits than its factorization.

11722640721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 679756.

The product of its (nonzero) digits is 9408, while the sum is 33.

The spelling of 11722640721 in words is "eleven billion, seven hundred twenty-two million, six hundred forty thousand, seven hundred twenty-one".