91815 has 8 divisors (see below), whose sum is σ = 146928. Its totient is φ = 48960.

The previous prime is 91813. The next prime is 91823. The reversal of 91815 is 51819.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 91815 - 2¹ = 91813 is a prime.

91815 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91811) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3046 + ... + 3075.

It is an arithmetic number, because the mean of its divisors is an integer number (18366).

2⁹¹⁸¹⁵ is an apocalyptic number.

91815 is a deficient number, since it is larger than the sum of its proper divisors (55113).

91815 is a wasteful number, since it uses less digits than its factorization.

91815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6129.

The product of its digits is 360, while the sum is 24.

The square root of 91815 is about 303.0099008283. The cubic root of 91815 is about 45.1132947697.

The spelling of 91815 in words is "ninety-one thousand, eight hundred fifteen".