90191391 has 4 divisors (see below), whose sum is σ = 120255192. Its totient is φ = 60127592.

The previous prime is 90191359. The next prime is 90191407. The reversal of 90191391 is 19319109.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19319109 = 3 ⋅6439703.

It is a cyclic number.

It is not a de Polignac number, because 90191391 - 2⁵ = 90191359 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90191291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15031896 + ... + 15031901.

It is an arithmetic number, because the mean of its divisors is an integer number (30063798).

Almost surely, 2^90191391 is an apocalyptic number.

90191391 is a deficient number, since it is larger than the sum of its proper divisors (30063801).

90191391 is a wasteful number, since it uses less digits than its factorization.

90191391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30063800.

The product of its (nonzero) digits is 2187, while the sum is 33.

The square root of 90191391 is about 9496.9148148228. The cubic root of 90191391 is about 448.4579166066.

The spelling of 90191391 in words is "ninety million, one hundred ninety-one thousand, three hundred ninety-one".