21122121091 has 2 divisors, whose sum is σ = 21122121092. Its totient is φ = 21122121090.

The previous prime is 21122121049. The next prime is 21122121101. The reversal of 21122121091 is 19012122112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21122121091 - 2¹¹ = 21122119043 is a prime.

It is a super-2 number, since 2×21122121091² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21122121491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561060545 + 10561060546.

It is an arithmetic number, because the mean of its divisors is an integer number (10561060546).

Almost surely, 2^21122121091 is an apocalyptic number.

21122121091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122121091 is an equidigital number, since it uses as much as digits as its factorization.

21122121091 is an evil number, because the sum of its binary digits is even.

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

The spelling of 21122121091 in words is "twenty-one billion, one hundred twenty-two million, one hundred twenty-one thousand, ninety-one".