21121011091 has 2 divisors, whose sum is σ = 21121011092. Its totient is φ = 21121011090.

The previous prime is 21121011077. The next prime is 21121011161. The reversal of 21121011091 is 19011012112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21121011091 - 2¹³ = 21121002899 is a prime.

It is a super-2 number, since 2×21121011091² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21121011001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560505545 + 10560505546.

It is an arithmetic number, because the mean of its divisors is an integer number (10560505546).

Almost surely, 2^21121011091 is an apocalyptic number.

21121011091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121011091 is an equidigital number, since it uses as much as digits as its factorization.

21121011091 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 21121011091 in words is "twenty-one billion, one hundred twenty-one million, eleven thousand, ninety-one".