91913281 has 2 divisors, whose sum is σ = 91913282. Its totient is φ = 91913280.

The previous prime is 91913273. The next prime is 91913323. The reversal of 91913281 is 18231919.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 82519056 + 9394225 = 9084^2 + 3065^2 .

It is a cyclic number.

It is not a de Polignac number, because 91913281 - 2³ = 91913273 is a prime.

It is a super-2 number, since 2×91913281² = 16896102448369922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (91913881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45956640 + 45956641.

It is an arithmetic number, because the mean of its divisors is an integer number (45956641).

Almost surely, 2^91913281 is an apocalyptic number.

91913281 is the 4288-th centered decagonal number.

It is an amenable number.

91913281 is a deficient number, since it is larger than the sum of its proper divisors (1).

91913281 is an equidigital number, since it uses as much as digits as its factorization.

91913281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 34.

The square root of 91913281 is about 9587.1414404921. The cubic root of 91913281 is about 451.2938581743.

The spelling of 91913281 in words is "ninety-one million, nine hundred thirteen thousand, two hundred eighty-one".