21101211091 has 2 divisors, whose sum is σ = 21101211092. Its totient is φ = 21101211090.

The previous prime is 21101211071. The next prime is 21101211179. The reversal of 21101211091 is 19011210112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21101211091 - 2⁵ = 21101211059 is a prime.

It is a super-2 number, since 2×21101211091² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21101211071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550605545 + 10550605546.

It is an arithmetic number, because the mean of its divisors is an integer number (10550605546).

Almost surely, 2^21101211091 is an apocalyptic number.

21101211091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21101211091 is an equidigital number, since it uses as much as digits as its factorization.

21101211091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36, while the sum is 19.

The spelling of 21101211091 in words is "twenty-one billion, one hundred one million, two hundred eleven thousand, ninety-one".