215640768 has 84 divisors (see below), whose sum is σ = 663729432. Its totient is φ = 61608960.

The previous prime is 215640739. The next prime is 215640809. The reversal of 215640768 is 867046512.

It is a tau number, because it is divible by the number of its divisors (84).

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 2053 + ... + 20868.

Almost surely, 2^215640768 is an apocalyptic number.

215640768 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 215640768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (331864716).

215640768 is an abundant number, since it is smaller than the sum of its proper divisors (448088664).

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

215640768 is a wasteful number, since it uses less digits than its factorization.

215640768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22950 (or 22933 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 39.

The square root of 215640768 is about 14684.7120502923. The cubic root of 215640768 is about 599.6671932113.

It can be divided in two parts, 2156 and 40768, that added together give a palindrome (42924).

The spelling of 215640768 in words is "two hundred fifteen million, six hundred forty thousand, seven hundred sixty-eight".