91691818 has 4 divisors (see below), whose sum is σ = 137537730. Its totient is φ = 45845908.

The previous prime is 91691813. The next prime is 91691833. The reversal of 91691818 is 81819619.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 90497169 + 1194649 = 9513^2 + 1093^2 .

It is not an unprimeable number, because it can be changed into a prime (91691813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 22922953 + ... + 22922956.

Almost surely, 2^91691818 is an apocalyptic number.

91691818 is a deficient number, since it is larger than the sum of its proper divisors (45845912).

91691818 is a wasteful number, since it uses less digits than its factorization.

91691818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45845911.

The product of its digits is 31104, while the sum is 43.

The square root of 91691818 is about 9575.5844730230. The cubic root of 91691818 is about 450.9311058425.

The spelling of 91691818 in words is "ninety-one million, six hundred ninety-one thousand, eight hundred eighteen".