21221211091 has 8 divisors (see below), whose sum is σ = 21723990464. Its totient is φ = 20718852840.

The previous prime is 21221211059. The next prime is 21221211097. The reversal of 21221211091 is 19011212212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21221211091 - 2⁵ = 21221211059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21221211097) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2121 + ... + 206026.

It is an arithmetic number, because the mean of its divisors is an integer number (2715498808).

Almost surely, 2^21221211091 is an apocalyptic number.

21221211091 is a deficient number, since it is larger than the sum of its proper divisors (502779373).

21221211091 is a wasteful number, since it uses less digits than its factorization.

21221211091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210561.

The product of its (nonzero) digits is 144, while the sum is 22.

It can be divided in two parts, 2122121 and 1091, that added together give a palindrome (2123212).

The spelling of 21221211091 in words is "twenty-one billion, two hundred twenty-one million, two hundred eleven thousand, ninety-one".