91631569 has 2 divisors, whose sum is σ = 91631570. Its totient is φ = 91631568.

The previous prime is 91631531. The next prime is 91631593. The reversal of 91631569 is 96513619.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 46580625 + 45050944 = 6825^2 + 6712^2 .

It is an emirp because it is prime and its reverse (96513619) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91631569 - 2¹⁹ = 91107281 is a prime.

It is a super-2 number, since 2×91631569² = 16792688874803522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (91631599) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45815784 + 45815785.

It is an arithmetic number, because the mean of its divisors is an integer number (45815785).

Almost surely, 2^91631569 is an apocalyptic number.

It is an amenable number.

91631569 is a deficient number, since it is larger than the sum of its proper divisors (1).

91631569 is an equidigital number, since it uses as much as digits as its factorization.

91631569 is an evil number, because the sum of its binary digits is even.

The product of its digits is 43740, while the sum is 40.

The square root of 91631569 is about 9572.4379862186. The cubic root of 91631569 is about 450.8323180353.

The spelling of 91631569 in words is "ninety-one million, six hundred thirty-one thousand, five hundred sixty-nine".