217822891225 has 27 divisors (see below), whose sum is σ = 271891751677. Its totient is φ = 173110194080.

The previous prime is 217822891217. The next prime is 217822891259. The reversal of 217822891225 is 522198228712.

The square root of 217822891225 is 466715.

It is a perfect power (a square), and thus also a powerful number.

217822891225 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 83550480601 + 134272410624 = 289051^2 + 366432^2 .

It is not a de Polignac number, because 217822891225 - 2³ = 217822891217 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 627731502 + ... + 627731848.

Almost surely, 2^217822891225 is an apocalyptic number.

217822891225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

217822891225 is the 466715-th square number.

217822891225 is the 233358-th centered octagonal number.

It is an amenable number.

217822891225 is a deficient number, since it is larger than the sum of its proper divisors (54068860452).

217822891225 is an frugal number, since it uses more digits than its factorization.

217822891225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1242 (or 621 counting only the distinct ones).

The product of its digits is 645120, while the sum is 49.

Multiplying 217822891225 by its sum of digits (49), we get a square (10673321670025 = 3267005²).

The spelling of 217822891225 in words is "two hundred seventeen billion, eight hundred twenty-two million, eight hundred ninety-one thousand, two hundred twenty-five".