215113581 has 6 divisors (see below), whose sum is σ = 310719630. Its totient is φ = 143409048.

The previous prime is 215113531. The next prime is 215113583. The reversal of 215113581 is 185311512.

215113581 is a `hidden beast` number, since 21 + 51 + 13 + 581 = 666.

It can be written as a sum of positive squares in only one way, i.e., 160427556 + 54686025 = 12666^2 + 7395^2 .

It is not a de Polignac number, because 215113581 - 2⁷ = 215113453 is a prime.

It is a super-2 number, since 2×215113581² = 92547705461287122, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215113583) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11950746 + ... + 11950763.

It is an arithmetic number, because the mean of its divisors is an integer number (51786605).

Almost surely, 2^215113581 is an apocalyptic number.

It is an amenable number.

215113581 is a deficient number, since it is larger than the sum of its proper divisors (95606049).

215113581 is a wasteful number, since it uses less digits than its factorization.

215113581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23901515 (or 23901512 counting only the distinct ones).

The product of its digits is 1200, while the sum is 27.

The square root of 215113581 is about 14666.7508671825. The cubic root of 215113581 is about 599.1781163595.

The spelling of 215113581 in words is "two hundred fifteen million, one hundred thirteen thousand, five hundred eighty-one".