91209971 has 2 divisors, whose sum is σ = 91209972. Its totient is φ = 91209970.

The previous prime is 91209961. The next prime is 91210027. The reversal of 91209971 is 17990219.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91209971 - 2¹⁴ = 91193587 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (91209961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45604985 + 45604986.

It is an arithmetic number, because the mean of its divisors is an integer number (45604986).

Almost surely, 2^91209971 is an apocalyptic number.

91209971 is a deficient number, since it is larger than the sum of its proper divisors (1).

91209971 is an equidigital number, since it uses as much as digits as its factorization.

91209971 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10206, while the sum is 38.

The square root of 91209971 is about 9550.3911438223. The cubic root of 91209971 is about 450.1398265067.

It can be divided in two parts, 9120 and 9971, that added together give a palindrome (19091).

The spelling of 91209971 in words is "ninety-one million, two hundred nine thousand, nine hundred seventy-one".