91236421 has 2 divisors, whose sum is σ = 91236422. Its totient is φ = 91236420.

The previous prime is 91236401. The next prime is 91236427. The reversal of 91236421 is 12463219.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 84916225 + 6320196 = 9215^2 + 2514^2 .

It is a cyclic number.

It is not a de Polignac number, because 91236421 - 2⁹ = 91235909 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 91236421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91236427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45618210 + 45618211.

It is an arithmetic number, because the mean of its divisors is an integer number (45618211).

Almost surely, 2^91236421 is an apocalyptic number.

It is an amenable number.

91236421 is a deficient number, since it is larger than the sum of its proper divisors (1).

91236421 is an equidigital number, since it uses as much as digits as its factorization.

91236421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 28.

The square root of 91236421 is about 9551.7758034828. The cubic root of 91236421 is about 450.1833343512.

The spelling of 91236421 in words is "ninety-one million, two hundred thirty-six thousand, four hundred twenty-one".