91145209 has 3 divisors (see below), whose sum is σ = 91154757. Its totient is φ = 91135662.

The previous prime is 91145179. The next prime is 91145269. The reversal of 91145209 is 90254119.

The square root of 91145209 is 9547.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a de Polignac number, because none of the positive numbers 2^k-91145209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91145269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4774 + ... + 14320.

It is an arithmetic number, because the mean of its divisors is an integer number (30384919).

Almost surely, 2^91145209 is an apocalyptic number.

91145209 is the 9547-th square number.

91145209 is the 4774-th centered octagonal number.

It is an amenable number.

91145209 is a deficient number, since it is larger than the sum of its proper divisors (9548).

91145209 is an frugal number, since it uses more digits than its factorization.

91145209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19094 (or 9547 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 31.

The cubic root of 91145209 is about 450.0332633848.

The spelling of 91145209 in words is "ninety-one million, one hundred forty-five thousand, two hundred nine".