91361821 has 2 divisors, whose sum is σ = 91361822. Its totient is φ = 91361820.

The previous prime is 91361807. The next prime is 91361833. The reversal of 91361821 is 12816319.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78322500 + 13039321 = 8850^2 + 3611^2 .

It is a cyclic number.

It is not a de Polignac number, because 91361821 - 2¹⁵ = 91329053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91361801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45680910 + 45680911.

It is an arithmetic number, because the mean of its divisors is an integer number (45680911).

Almost surely, 2^91361821 is an apocalyptic number.

It is an amenable number.

91361821 is a deficient number, since it is larger than the sum of its proper divisors (1).

91361821 is an equidigital number, since it uses as much as digits as its factorization.

91361821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 31.

The square root of 91361821 is about 9558.3377739019. The cubic root of 91361821 is about 450.3894915900.

The spelling of 91361821 in words is "ninety-one million, three hundred sixty-one thousand, eight hundred twenty-one".