209240905 has 16 divisors (see below), whose sum is σ = 256172544. Its totient is φ = 164032960.

The previous prime is 209240903. The next prime is 209240909. The reversal of 209240905 is 509042902.

It is not a de Polignac number, because 209240905 - 2¹ = 209240903 is a prime.

It is not an unprimeable number, because it can be changed into a prime (209240903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 59712 + ... + 63118.

It is an arithmetic number, because the mean of its divisors is an integer number (16010784).

Almost surely, 2^209240905 is an apocalyptic number.

It is an amenable number.

209240905 is a deficient number, since it is larger than the sum of its proper divisors (46931639).

209240905 is a wasteful number, since it uses less digits than its factorization.

209240905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3656.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 209240905 is about 14465.1617688846. The cubic root of 209240905 is about 593.6751398880.

The spelling of 209240905 in words is "two hundred nine million, two hundred forty thousand, nine hundred five".