91621571 has 2 divisors, whose sum is σ = 91621572. Its totient is φ = 91621570.

The previous prime is 91621567. The next prime is 91621603. The reversal of 91621571 is 17512619.

It is an a-pointer prime, because the next prime (91621603) can be obtained adding 91621571 to its sum of digits (32).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91621571 - 2² = 91621567 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (91681571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45810785 + 45810786.

It is an arithmetic number, because the mean of its divisors is an integer number (45810786).

Almost surely, 2^91621571 is an apocalyptic number.

91621571 is a deficient number, since it is larger than the sum of its proper divisors (1).

91621571 is an equidigital number, since it uses as much as digits as its factorization.

91621571 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3780, while the sum is 32.

The square root of 91621571 is about 9571.9157434654. The cubic root of 91621571 is about 450.8159205371.

The spelling of 91621571 in words is "ninety-one million, six hundred twenty-one thousand, five hundred seventy-one".