21203430091 has 2 divisors, whose sum is σ = 21203430092. Its totient is φ = 21203430090.

The previous prime is 21203430007. The next prime is 21203430097. The reversal of 21203430091 is 19003430212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21203430091 - 2¹⁵ = 21203397323 is a prime.

It is not a weakly prime, because it can be changed into another prime (21203430097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601715045 + 10601715046.

It is an arithmetic number, because the mean of its divisors is an integer number (10601715046).

Almost surely, 2^21203430091 is an apocalyptic number.

21203430091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21203430091 is an equidigital number, since it uses as much as digits as its factorization.

21203430091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 25.

The spelling of 21203430091 in words is "twenty-one billion, two hundred three million, four hundred thirty thousand, ninety-one".