215551656 has 72 divisors (see below), whose sum is σ = 616202730. Its totient is φ = 68060736.

The previous prime is 215551643. The next prime is 215551673. The reversal of 215551656 is 656155512.

It can be written as a sum of positive squares in only one way, i.e., 203062500 + 12489156 = 14250^2 + 3534^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 215551656.

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 17 ways as a sum of consecutive naturals, for example, 21846 + ... + 30138.

Almost surely, 2^215551656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 215551656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (308101365).

215551656 is an abundant number, since it is smaller than the sum of its proper divisors (400651074).

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

215551656 is a wasteful number, since it uses less digits than its factorization.

215551656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8343 (or 8317 counting only the distinct ones).

The product of its digits is 45000, while the sum is 36.

The square root of 215551656 is about 14681.6775608239. The cubic root of 215551656 is about 599.5845791089.

The spelling of 215551656 in words is "two hundred fifteen million, five hundred fifty-one thousand, six hundred fifty-six".