91039997 has 2 divisors, whose sum is σ = 91039998. Its totient is φ = 91039996.

The previous prime is 91039933. The next prime is 91040023. The reversal of 91039997 is 79993019.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 87123556 + 3916441 = 9334^2 + 1979^2 .

It is an emirp because it is prime and its reverse (79993019) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91039997 - 2⁶ = 91039933 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91036997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45519998 + 45519999.

It is an arithmetic number, because the mean of its divisors is an integer number (45519999).

Almost surely, 2^91039997 is an apocalyptic number.

It is an amenable number.

91039997 is a deficient number, since it is larger than the sum of its proper divisors (1).

91039997 is an equidigital number, since it uses as much as digits as its factorization.

91039997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 137781, while the sum is 47.

The square root of 91039997 is about 9541.4881962931. The cubic root of 91039997 is about 449.8600338363.

The spelling of 91039997 in words is "ninety-one million, thirty-nine thousand, nine hundred ninety-seven".