209403081 has 12 divisors (see below), whose sum is σ = 302631108. Its totient is φ = 139528224.

The previous prime is 209403043. The next prime is 209403097. The reversal of 209403081 is 180304902.

It can be written as a sum of positive squares in 2 ways, for example, as 46457856 + 162945225 = 6816^2 + 12765^2 .

It is not a de Polignac number, because 209403081 - 2¹⁰ = 209402057 is a prime.

It is a super-2 number, since 2×209403081² = 87699300664585122, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (209403281) 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, 16011 + ... + 25983.

It is an arithmetic number, because the mean of its divisors is an integer number (25219259).

Almost surely, 2^209403081 is an apocalyptic number.

It is an amenable number.

209403081 is a deficient number, since it is larger than the sum of its proper divisors (93228027).

209403081 is a wasteful number, since it uses less digits than its factorization.

209403081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12312 (or 12309 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 209403081 is about 14470.7664275255. The cubic root of 209403081 is about 593.8284798793.

Adding to 209403081 its reverse (180304902), we get a palindrome (389707983).

The spelling of 209403081 in words is "two hundred nine million, four hundred three thousand, eighty-one".