21102121191 has 4 divisors (see below), whose sum is σ = 28136161592. Its totient is φ = 14068080792.

The previous prime is 21102121153. The next prime is 21102121217. The reversal of 21102121191 is 19112120112.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21102121191 - 2¹⁸ = 21101859047 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 (21102121141) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3517020196 + ... + 3517020201.

It is an arithmetic number, because the mean of its divisors is an integer number (7034040398).

Almost surely, 2^21102121191 is an apocalyptic number.

21102121191 is a deficient number, since it is larger than the sum of its proper divisors (7034040401).

21102121191 is an equidigital number, since it uses as much as digits as its factorization.

21102121191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7034040400.

The product of its (nonzero) digits is 72, while the sum is 21.

The spelling of 21102121191 in words is "twenty-one billion, one hundred two million, one hundred twenty-one thousand, one hundred ninety-one".