215732681 has 4 divisors (see below), whose sum is σ = 221563332. Its totient is φ = 209902032.

The previous prime is 215732659. The next prime is 215732683. The reversal of 215732681 is 186237512.

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 200647225 + 15085456 = 14165^2 + 3884^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215732681 is a prime.

It is a super-2 number, since 2×215732681² = 93081179302895522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (215732683) 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, 2915270 + ... + 2915343.

It is an arithmetic number, because the mean of its divisors is an integer number (55390833).

Almost surely, 2^215732681 is an apocalyptic number.

It is an amenable number.

215732681 is a deficient number, since it is larger than the sum of its proper divisors (5830651).

215732681 is an equidigital number, since it uses as much as digits as its factorization.

215732681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5830650.

The product of its digits is 20160, while the sum is 35.

The square root of 215732681 is about 14687.8412641205. The cubic root of 215732681 is about 599.7523802289.

The spelling of 215732681 in words is "two hundred fifteen million, seven hundred thirty-two thousand, six hundred eighty-one".