21001222191 has 16 divisors (see below), whose sum is σ = 29698099200. Its totient is φ = 13172538720.

The previous prime is 21001222189. The next prime is 21001222219. The reversal of 21001222191 is 19122210012.

It is not a de Polignac number, because 21001222191 - 2¹ = 21001222189 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001222181) 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, 2490591 + ... + 2499008.

It is an arithmetic number, because the mean of its divisors is an integer number (1856131200).

Almost surely, 2^21001222191 is an apocalyptic number.

21001222191 is a deficient number, since it is larger than the sum of its proper divisors (8696877009).

21001222191 is a wasteful number, since it uses less digits than its factorization.

21001222191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4989686.

The product of its (nonzero) digits is 144, while the sum is 21.

The spelling of 21001222191 in words is "twenty-one billion, one million, two hundred twenty-two thousand, one hundred ninety-one".