91000000921 has 2 divisors, whose sum is σ = 91000000922. Its totient is φ = 91000000920.

The previous prime is 91000000891. The next prime is 91000000937. The reversal of 91000000921 is 12900000019.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 87675210000 + 3324790921 = 296100^2 + 57661^2 .

It is a cyclic number.

It is not a de Polignac number, because 91000000921 - 2³³ = 82410066329 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 91000000892 and 91000000901.

It is not a weakly prime, because it can be changed into another prime (91000000981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45500000460 + 45500000461.

It is an arithmetic number, because the mean of its divisors is an integer number (45500000461).

Almost surely, 2^91000000921 is an apocalyptic number.

It is an amenable number.

91000000921 is a deficient number, since it is larger than the sum of its proper divisors (1).

91000000921 is an equidigital number, since it uses as much as digits as its factorization.

91000000921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 162, while the sum is 22.

The spelling of 91000000921 in words is "ninety-one billion, nine hundred twenty-one", and thus it is an aban number.