91209391 has 16 divisors (see below), whose sum is σ = 113425984. Its totient is φ = 71414784.

The previous prime is 91209373. The next prime is 91209401. The reversal of 91209391 is 19390219.

It is not a de Polignac number, because 91209391 - 2⁵ = 91209359 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91209341) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3661 + ... + 13993.

It is an arithmetic number, because the mean of its divisors is an integer number (7089124).

Almost surely, 2^91209391 is an apocalyptic number.

91209391 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

91209391 is a deficient number, since it is larger than the sum of its proper divisors (22216593).

91209391 is a wasteful number, since it uses less digits than its factorization.

91209391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10450.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 91209391 is about 9550.3607785256. The cubic root of 91209391 is about 450.1388723652.

The spelling of 91209391 in words is "ninety-one million, two hundred nine thousand, three hundred ninety-one".