91021481 has 2 divisors, whose sum is σ = 91021482. Its totient is φ = 91021480.

The previous prime is 91021453. The next prime is 91021493. The reversal of 91021481 is 18412019.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79049881 + 11971600 = 8891^2 + 3460^2 .

It is a cyclic number.

It is not a de Polignac number, because 91021481 - 2¹⁸ = 90759337 is a prime.

It is a super-2 number, since 2×91021481² = 16569820006866722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 91021481.

It is not a weakly prime, because it can be changed into another prime (91021421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45510740 + 45510741.

It is an arithmetic number, because the mean of its divisors is an integer number (45510741).

Almost surely, 2^91021481 is an apocalyptic number.

It is an amenable number.

91021481 is a deficient number, since it is larger than the sum of its proper divisors (1).

91021481 is an equidigital number, since it uses as much as digits as its factorization.

91021481 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 91021481 is about 9540.5178580620. The cubic root of 91021481 is about 449.8295337871.

The spelling of 91021481 in words is "ninety-one million, twenty-one thousand, four hundred eighty-one".