215978868 has 72 divisors (see below), whose sum is σ = 636708800. Its totient is φ = 61704720.

The previous prime is 215978843. The next prime is 215978899. The reversal of 215978868 is 868879512.

It is a super-2 number, since 2×215978868² = 93293742845122848, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 3603 + ... + 21093.

Almost surely, 2^215978868 is an apocalyptic number.

215978868 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 215978868, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (318354400).

215978868 is an abundant number, since it is smaller than the sum of its proper divisors (420729932).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

215978868 is a wasteful number, since it uses less digits than its factorization.

215978868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17522 (or 17503 counting only the distinct ones).

The product of its digits is 1935360, while the sum is 54.

The square root of 215978868 is about 14696.2195138750. The cubic root of 215978868 is about 599.9804326952.

The spelling of 215978868 in words is "two hundred fifteen million, nine hundred seventy-eight thousand, eight hundred sixty-eight".