18261809 has 2 divisors, whose sum is σ = 18261810. Its totient is φ = 18261808.

The previous prime is 18261787. The next prime is 18261827. The reversal of 18261809 is 90816281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11122225 + 7139584 = 3335^2 + 2672^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18261809 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18261829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9130904 + 9130905.

It is an arithmetic number, because the mean of its divisors is an integer number (9130905).

Almost surely, 2^18261809 is an apocalyptic number.

It is an amenable number.

18261809 is a deficient number, since it is larger than the sum of its proper divisors (1).

18261809 is an equidigital number, since it uses as much as digits as its factorization.

18261809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 18261809 is about 4273.3837880537. The cubic root of 18261809 is about 263.3386462992.

The spelling of 18261809 in words is "eighteen million, two hundred sixty-one thousand, eight hundred nine".