209985725 has 6 divisors (see below), whose sum is σ = 260382330. Its totient is φ = 167988560.

The previous prime is 209985691. The next prime is 209985731. The reversal of 209985725 is 527589902.

It can be written as a sum of positive squares in 3 ways, for example, as 26491609 + 183494116 = 5147^2 + 13546^2 .

It is not a de Polignac number, because 209985725 - 2¹⁴ = 209969341 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 209985725.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4199690 + ... + 4199739.

It is an arithmetic number, because the mean of its divisors is an integer number (43397055).

Almost surely, 2^209985725 is an apocalyptic number.

209985725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

209985725 is a deficient number, since it is larger than the sum of its proper divisors (50396605).

209985725 is an equidigital number, since it uses as much as digits as its factorization.

209985725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8399439 (or 8399434 counting only the distinct ones).

The product of its (nonzero) digits is 453600, while the sum is 47.

The square root of 209985725 is about 14490.8842035260. The cubic root of 209985725 is about 594.3787267988.

The spelling of 209985725 in words is "two hundred nine million, nine hundred eighty-five thousand, seven hundred twenty-five".