21221001091 has 16 divisors (see below), whose sum is σ = 21875318784. Its totient is φ = 20577023584.

The previous prime is 21221001059. The next prime is 21221001097. The reversal of 21221001091 is 19010012212.

It is a happy number.

It is not a de Polignac number, because 21221001091 - 2⁵ = 21221001059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21221001097) 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 15 ways as a sum of consecutive naturals, for example, 2508030 + ... + 2516476.

It is an arithmetic number, because the mean of its divisors is an integer number (1367207424).

Almost surely, 2^21221001091 is an apocalyptic number.

21221001091 is a deficient number, since it is larger than the sum of its proper divisors (654317693).

21221001091 is a wasteful number, since it uses less digits than its factorization.

21221001091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9050.

The product of its (nonzero) digits is 72, while the sum is 19.

The spelling of 21221001091 in words is "twenty-one billion, two hundred twenty-one million, one thousand, ninety-one".