21909911121 has 24 divisors (see below), whose sum is σ = 36259888704. Its totient is φ = 12488398560.

The previous prime is 21909911069. The next prime is 21909911143. The reversal of 21909911121 is 12111990912.

It is not a de Polignac number, because 21909911121 - 2¹³ = 21909902929 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21909911171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 412995 + ... + 463016.

It is an arithmetic number, because the mean of its divisors is an integer number (1510828696).

Almost surely, 2^21909911121 is an apocalyptic number.

21909911121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21909911121 is a deficient number, since it is larger than the sum of its proper divisors (14349977583).

21909911121 is a wasteful number, since it uses less digits than its factorization.

21909911121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 876421 (or 876418 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 36.

The spelling of 21909911121 in words is "twenty-one billion, nine hundred nine million, nine hundred eleven thousand, one hundred twenty-one".