209561139 has 12 divisors (see below), whose sum is σ = 306347496. Its totient is φ = 138023712.

The previous prime is 209561101. The next prime is 209561153. The reversal of 209561139 is 931165902.

209561139 is a `hidden beast` number, since 2 + 0 + 9 + 5 + 611 + 39 = 666.

It is not a de Polignac number, because 209561139 - 2¹² = 209557043 is a prime.

It is not an unprimeable number, because it can be changed into a prime (209561039) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 139522 + ... + 141015.

It is an arithmetic number, because the mean of its divisors is an integer number (25528958).

Almost surely, 2^209561139 is an apocalyptic number.

209561139 is a deficient number, since it is larger than the sum of its proper divisors (96786357).

209561139 is a wasteful number, since it uses less digits than its factorization.

209561139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280626 (or 280623 counting only the distinct ones).

The product of its (nonzero) digits is 14580, while the sum is 36.

The square root of 209561139 is about 14476.2266837736. The cubic root of 209561139 is about 593.9778500736.

The spelling of 209561139 in words is "two hundred nine million, five hundred sixty-one thousand, one hundred thirty-nine".