209805222025 has 81 divisors (see below), whose sum is σ = 316920360981. Its totient is φ = 137369527680.

The previous prime is 209805221993. The next prime is 209805222037. The reversal of 209805222025 is 520222508902.

The square root of 209805222025 is 458045.

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

It can be written as a sum of positive squares in 4 ways, for example, as 49866016249 + 159939205776 = 223307^2 + 399924^2 .

It is not a de Polignac number, because 209805222025 - 2⁵ = 209805221993 is a prime.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

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 80 ways as a sum of consecutive naturals, for example, 368725941 + ... + 368726509.

Almost surely, 2^209805222025 is an apocalyptic number.

209805222025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

209805222025 is the 458045-th square number.

209805222025 is the 229023-rd centered octagonal number.

It is an amenable number.

209805222025 is a deficient number, since it is larger than the sum of its proper divisors (107115138956).

209805222025 is an frugal number, since it uses more digits than its factorization.

209805222025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1208 (or 604 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 37.

The spelling of 209805222025 in words is "two hundred nine billion, eight hundred five million, two hundred twenty-two thousand, twenty-five".