209561057 has 6 divisors (see below), whose sum is σ = 221951394. Its totient is φ = 197177760.

The previous prime is 209561041. The next prime is 209561069. The reversal of 209561057 is 750165902.

It can be written as a sum of positive squares in only one way, i.e., 197233936 + 12327121 = 14044^2 + 3511^2 .

It is not a de Polignac number, because 209561057 - 2⁴ = 209561041 is a prime.

It is a super-2 number, since 2×209561057² = 87831673221914498, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209561017) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 57932 + ... + 61442.

It is an arithmetic number, because the mean of its divisors is an integer number (36991899).

Almost surely, 2^209561057 is an apocalyptic number.

It is an amenable number.

209561057 is a deficient number, since it is larger than the sum of its proper divisors (12390337).

209561057 is an frugal number, since it uses more digits than its factorization.

209561057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7039 (or 3528 counting only the distinct ones).

The product of its (nonzero) digits is 18900, while the sum is 35.

The square root of 209561057 is about 14476.2238515436. The cubic root of 209561057 is about 593.9777726003.

The spelling of 209561057 in words is "two hundred nine million, five hundred sixty-one thousand, fifty-seven".