209440139 has 16 divisors (see below), whose sum is σ = 224486400. Its totient is φ = 194965056.

The previous prime is 209440111. The next prime is 209440141. The reversal of 209440139 is 931044902.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 209440139 - 2¹⁶ = 209374603 is a prime.

It is not an unprimeable number, because it can be changed into a prime (209440109) 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 15 ways as a sum of consecutive naturals, for example, 131852 + ... + 133430.

It is an arithmetic number, because the mean of its divisors is an integer number (14030400).

Almost surely, 2^209440139 is an apocalyptic number.

209440139 is a deficient number, since it is larger than the sum of its proper divisors (15046261).

209440139 is a wasteful number, since it uses less digits than its factorization.

209440139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1754.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 209440139 is about 14472.0468144627. The cubic root of 209440139 is about 593.8635076954.

The spelling of 209440139 in words is "two hundred nine million, four hundred forty thousand, one hundred thirty-nine".