209157705 has 24 divisors (see below), whose sum is σ = 366285192. Its totient is φ = 110398464.

The previous prime is 209157703. The next prime is 209157727. The reversal of 209157705 is 507751902.

It can be written as a sum of positive squares in 4 ways, for example, as 1192464 + 207965241 = 1092^2 + 14421^2 .

It is not a de Polignac number, because 209157705 - 2¹ = 209157703 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 209157705.

It is not an unprimeable number, because it can be changed into a prime (209157701) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 19594 + ... + 28323.

It is an arithmetic number, because the mean of its divisors is an integer number (15261883).

Almost surely, 2^209157705 is an apocalyptic number.

It is an amenable number.

209157705 is a deficient number, since it is larger than the sum of its proper divisors (157127487).

209157705 is a wasteful number, since it uses less digits than its factorization.

209157705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48025 (or 48022 counting only the distinct ones).

The product of its (nonzero) digits is 22050, while the sum is 36.

The square root of 209157705 is about 14462.2856077454. The cubic root of 209157705 is about 593.5964422103.

The spelling of 209157705 in words is "two hundred nine million, one hundred fifty-seven thousand, seven hundred five".