91563421 has 2 divisors, whose sum is σ = 91563422. Its totient is φ = 91563420.

The previous prime is 91563397. The next prime is 91563443. The reversal of 91563421 is 12436519.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 90535225 + 1028196 = 9515^2 + 1014^2 .

It is a cyclic number.

It is not a de Polignac number, because 91563421 - 2¹¹ = 91561373 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91563481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45781710 + 45781711.

It is an arithmetic number, because the mean of its divisors is an integer number (45781711).

Almost surely, 2^91563421 is an apocalyptic number.

It is an amenable number.

91563421 is a deficient number, since it is larger than the sum of its proper divisors (1).

91563421 is an equidigital number, since it uses as much as digits as its factorization.

91563421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6480, while the sum is 31.

The square root of 91563421 is about 9568.8777293892. The cubic root of 91563421 is about 450.7205263577.

The spelling of 91563421 in words is "ninety-one million, five hundred sixty-three thousand, four hundred twenty-one".