91189381 has 2 divisors, whose sum is σ = 91189382. Its totient is φ = 91189380.

The previous prime is 91189363. The next prime is 91189387. The reversal of 91189381 is 18398119.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 47748100 + 43441281 = 6910^2 + 6591^2 .

It is a cyclic number.

It is not a de Polignac number, because 91189381 - 2¹¹ = 91187333 is a prime.

It is a super-2 number, since 2×91189381² = 16631006414326322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91189387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45594690 + 45594691.

It is an arithmetic number, because the mean of its divisors is an integer number (45594691).

Almost surely, 2^91189381 is an apocalyptic number.

It is an amenable number.

91189381 is a deficient number, since it is larger than the sum of its proper divisors (1).

91189381 is an equidigital number, since it uses as much as digits as its factorization.

91189381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 40.

The square root of 91189381 is about 9549.3131166592. The cubic root of 91189381 is about 450.1059520065.

The spelling of 91189381 in words is "ninety-one million, one hundred eighty-nine thousand, three hundred eighty-one".