91955821 has 2 divisors, whose sum is σ = 91955822. Its totient is φ = 91955820.

The previous prime is 91955819. The next prime is 91955833. The reversal of 91955821 is 12855919.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 88153321 + 3802500 = 9389^2 + 1950^2 .

It is a cyclic number.

It is not a de Polignac number, because 91955821 - 2¹ = 91955819 is a prime.

Together with 91955819, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91955861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45977910 + 45977911.

It is an arithmetic number, because the mean of its divisors is an integer number (45977911).

Almost surely, 2^91955821 is an apocalyptic number.

It is an amenable number.

91955821 is a deficient number, since it is larger than the sum of its proper divisors (1).

91955821 is an equidigital number, since it uses as much as digits as its factorization.

91955821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32400, while the sum is 40.

The square root of 91955821 is about 9589.3597805067. The cubic root of 91955821 is about 451.3634711815.

The spelling of 91955821 in words is "ninety-one million, nine hundred fifty-five thousand, eight hundred twenty-one".