11721051221 has 16 divisors (see below), whose sum is σ = 13092383808. Its totient is φ = 10403500800.

The previous prime is 11721051211. The next prime is 11721051239. The reversal of 11721051221 is 12215012711.

It is a happy number.

It is not a de Polignac number, because 11721051221 - 2¹⁴ = 11721034837 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11721051211) 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, 12911 + ... + 153651.

It is an arithmetic number, because the mean of its divisors is an integer number (818273988).

Almost surely, 2^11721051221 is an apocalyptic number.

11721051221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11721051221 is a deficient number, since it is larger than the sum of its proper divisors (1371332587).

11721051221 is a wasteful number, since it uses less digits than its factorization.

11721051221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140932.

The product of its (nonzero) digits is 280, while the sum is 23.

Adding to 11721051221 its reverse (12215012711), we get a palindrome (23936063932).

The spelling of 11721051221 in words is "eleven billion, seven hundred twenty-one million, fifty-one thousand, two hundred twenty-one".