215091 has 6 divisors (see below), whose sum is σ = 310700. Its totient is φ = 143388.

The previous prime is 215087. The next prime is 215123. The reversal of 215091 is 190512.

It is not a de Polignac number, because 215091 - 2² = 215087 is a prime.

It is a Duffinian number.

215091 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (215051) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11941 + ... + 11958.

2²¹⁵⁰⁹¹ is an apocalyptic number.

215091 is a deficient number, since it is larger than the sum of its proper divisors (95609).

215091 is a wasteful number, since it uses less digits than its factorization.

215091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23905 (or 23902 counting only the distinct ones).

The product of its (nonzero) digits is 90, while the sum is 18.

The square root of 215091 is about 463.7790422173. The cubic root of 215091 is about 59.9157149894.

The spelling of 215091 in words is "two hundred fifteen thousand, ninety-one".