91621 has 2 divisors, whose sum is σ = 91622. Its totient is φ = 91620.

The previous prime is 91591. The next prime is 91631. The reversal of 91621 is 12619.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 83521 + 8100 = 289^2 + 90^2 .

It is an emirp because it is prime and its reverse (12619) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91621 - 2⁷ = 91493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45810 + 45811.

It is an arithmetic number, because the mean of its divisors is an integer number (45811).

2⁹¹⁶²¹ is an apocalyptic number.

It is an amenable number.

91621 is a deficient number, since it is larger than the sum of its proper divisors (1).

91621 is an equidigital number, since it uses as much as digits as its factorization.

91621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108, while the sum is 19.

The square root of 91621 is about 302.6896099968. The cubic root of 91621 is about 45.0814984017.

The spelling of 91621 in words is "ninety-one thousand, six hundred twenty-one".