91921 has 2 divisors, whose sum is σ = 91922. Its totient is φ = 91920.

The previous prime is 91909. The next prime is 91939. The reversal of 91921 is 12919.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65025 + 26896 = 255^2 + 164^2 .

It is an emirp because it is prime and its reverse (12919) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91921 is a prime.

91921 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 91892 and 91901.

It is not a weakly prime, because it can be changed into another prime (91951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45960 + 45961.

It is an arithmetic number, because the mean of its divisors is an integer number (45961).

2⁹¹⁹²¹ is an apocalyptic number.

It is an amenable number.

91921 is a deficient number, since it is larger than the sum of its proper divisors (1).

91921 is an equidigital number, since it uses as much as digits as its factorization.

91921 is an evil number, because the sum of its binary digits is even.

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

The square root of 91921 is about 303.1847621501. The cubic root of 91921 is about 45.1306491241.

The spelling of 91921 in words is "ninety-one thousand, nine hundred twenty-one".