91811939 has 2 divisors, whose sum is σ = 91811940. Its totient is φ = 91811938.

The previous prime is 91811903. The next prime is 91811947. The reversal of 91811939 is 93911819.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 91811939 - 2¹² = 91807843 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 91811896 and 91811905.

It is not a weakly prime, because it can be changed into another prime (91811959) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45905969 + 45905970.

It is an arithmetic number, because the mean of its divisors is an integer number (45905970).

Almost surely, 2^91811939 is an apocalyptic number.

91811939 is a deficient number, since it is larger than the sum of its proper divisors (1).

91811939 is an equidigital number, since it uses as much as digits as its factorization.

91811939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17496, while the sum is 41.

The square root of 91811939 is about 9581.8546743311. The cubic root of 91811939 is about 451.1279342336.

The spelling of 91811939 in words is "ninety-one million, eight hundred eleven thousand, nine hundred thirty-nine".