215966881 has 4 divisors (see below), whose sum is σ = 232579732. Its totient is φ = 199354032.

The previous prime is 215966869. The next prime is 215966893. The reversal of 215966881 is 188669512.

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

It is an interprime number because it is at equal distance from previous prime (215966869) and next prime (215966893).

It can be written as a sum of positive squares in 2 ways, for example, as 60590656 + 155376225 = 7784^2 + 12465^2 .

It is a cyclic number.

It is not a de Polignac number, because 215966881 - 2⁷ = 215966753 is a prime.

It is a super-3 number, since 3×215966881³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (215966831) 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, 8306406 + ... + 8306431.

It is an arithmetic number, because the mean of its divisors is an integer number (58144933).

Almost surely, 2^215966881 is an apocalyptic number.

It is an amenable number.

215966881 is a deficient number, since it is larger than the sum of its proper divisors (16612851).

215966881 is a wasteful number, since it uses less digits than its factorization.

215966881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16612850.

The product of its digits is 207360, while the sum is 46.

The square root of 215966881 is about 14695.8116822447. The cubic root of 215966881 is about 599.9693326918.

The spelling of 215966881 in words is "two hundred fifteen million, nine hundred sixty-six thousand, eight hundred eighty-one".