215449891 has 4 divisors (see below), whose sum is σ = 228123432. Its totient is φ = 202776352.

The previous prime is 215449877. The next prime is 215449921. The reversal of 215449891 is 198944512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 215449891 - 2¹⁹ = 214925603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (215449811) 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, 6336745 + ... + 6336778.

It is an arithmetic number, because the mean of its divisors is an integer number (57030858).

Almost surely, 2^215449891 is an apocalyptic number.

215449891 is a deficient number, since it is larger than the sum of its proper divisors (12673541).

215449891 is a wasteful number, since it uses less digits than its factorization.

215449891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12673540.

The product of its digits is 103680, while the sum is 43.

The square root of 215449891 is about 14678.2114373652. The cubic root of 215449891 is about 599.4902067890.

The spelling of 215449891 in words is "two hundred fifteen million, four hundred forty-nine thousand, eight hundred ninety-one".