91099621 has 2 divisors, whose sum is σ = 91099622. Its totient is φ = 91099620.

The previous prime is 91099609. The next prime is 91099691. The reversal of 91099621 is 12699019.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 88172100 + 2927521 = 9390^2 + 1711^2 .

It is a cyclic number.

It is not a de Polignac number, because 91099621 - 2⁷ = 91099493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91099691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45549810 + 45549811.

It is an arithmetic number, because the mean of its divisors is an integer number (45549811).

Almost surely, 2^91099621 is an apocalyptic number.

It is an amenable number.

91099621 is a deficient number, since it is larger than the sum of its proper divisors (1).

91099621 is an equidigital number, since it uses as much as digits as its factorization.

91099621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8748, while the sum is 37.

The square root of 91099621 is about 9544.6121450795. The cubic root of 91099621 is about 449.9582199894.

The spelling of 91099621 in words is "ninety-one million, ninety-nine thousand, six hundred twenty-one".