21020110091 has 2 divisors, whose sum is σ = 21020110092. Its totient is φ = 21020110090.

The previous prime is 21020110087. The next prime is 21020110121. The reversal of 21020110091 is 19001102012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21020110091 - 2² = 21020110087 is a prime.

It is not a weakly prime, because it can be changed into another prime (21020115091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510055045 + 10510055046.

It is an arithmetic number, because the mean of its divisors is an integer number (10510055046).

Almost surely, 2^21020110091 is an apocalyptic number.

21020110091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020110091 is an equidigital number, since it uses as much as digits as its factorization.

21020110091 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 17.

The spelling of 21020110091 in words is "twenty-one billion, twenty million, one hundred ten thousand, ninety-one".