261818939 has 2 divisors, whose sum is σ = 261818940. Its totient is φ = 261818938.

The previous prime is 261818929. The next prime is 261818941. The reversal of 261818939 is 939818162.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261818939 is a prime.

It is a Sophie Germain prime.

Together with 261818941, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 261818893 and 261818902.

It is not a weakly prime, because it can be changed into another prime (261818929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130909469 + 130909470.

It is an arithmetic number, because the mean of its divisors is an integer number (130909470).

Almost surely, 2^261818939 is an apocalyptic number.

261818939 is a deficient number, since it is larger than the sum of its proper divisors (1).

261818939 is an equidigital number, since it uses as much as digits as its factorization.

261818939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 186624, while the sum is 47.

The square root of 261818939 is about 16180.8200966453. The cubic root of 261818939 is about 639.7353552635.

The spelling of 261818939 in words is "two hundred sixty-one million, eight hundred eighteen thousand, nine hundred thirty-nine".