21213202091 has 2 divisors, whose sum is σ = 21213202092. Its totient is φ = 21213202090.

The previous prime is 21213202081. The next prime is 21213202103. The reversal of 21213202091 is 19020231212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21213202091 - 2⁶ = 21213202027 is a prime.

It is not a weakly prime, because it can be changed into another prime (21213202081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606601045 + 10606601046.

It is an arithmetic number, because the mean of its divisors is an integer number (10606601046).

Almost surely, 2^21213202091 is an apocalyptic number.

21213202091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213202091 is an equidigital number, since it uses as much as digits as its factorization.

21213202091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 23.

The spelling of 21213202091 in words is "twenty-one billion, two hundred thirteen million, two hundred two thousand, ninety-one".