90197815 has 4 divisors (see below), whose sum is σ = 108237384. Its totient is φ = 72158248.

The previous prime is 90197803. The next prime is 90197839. The reversal of 90197815 is 51879109.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51879109 = 139 ⋅373231.

It is a cyclic number.

It is not a de Polignac number, because 90197815 - 2¹¹ = 90195767 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9019777 + ... + 9019786.

It is an arithmetic number, because the mean of its divisors is an integer number (27059346).

Almost surely, 2^90197815 is an apocalyptic number.

90197815 is a deficient number, since it is larger than the sum of its proper divisors (18039569).

90197815 is a wasteful number, since it uses less digits than its factorization.

90197815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18039568.

The product of its (nonzero) digits is 22680, while the sum is 40.

The square root of 90197815 is about 9497.2530239012. The cubic root of 90197815 is about 448.4685636880.

The spelling of 90197815 in words is "ninety million, one hundred ninety-seven thousand, eight hundred fifteen".