215994389 has 4 divisors (see below), whose sum is σ = 232609356. Its totient is φ = 199379424.

The previous prime is 215994379. The next prime is 215994431. The reversal of 215994389 is 983499512.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 127012900 + 88981489 = 11270^2 + 9433^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215994389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215994319) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8307464 + ... + 8307489.

It is an arithmetic number, because the mean of its divisors is an integer number (58152339).

Almost surely, 2^215994389 is an apocalyptic number.

It is an amenable number.

215994389 is a deficient number, since it is larger than the sum of its proper divisors (16614967).

215994389 is a wasteful number, since it uses less digits than its factorization.

215994389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16614966.

The product of its digits is 699840, while the sum is 50.

The square root of 215994389 is about 14696.7475653629. The cubic root of 215994389 is about 599.9948045846.

The spelling of 215994389 in words is "two hundred fifteen million, nine hundred ninety-four thousand, three hundred eighty-nine".