18205815949 has 4 divisors (see below), whose sum is σ = 18235809664. Its totient is φ = 18175822236.

The previous prime is 18205815907. The next prime is 18205816009. The reversal of 18205815949 is 94951850281.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 94951850281 = 65993 ⋅1438817.

It is a cyclic number.

It is not a de Polignac number, because 18205815949 - 2¹⁵ = 18205783181 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18205815896 and 18205815905.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18205818949) 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 3 ways as a sum of consecutive naturals, for example, 14995947 + ... + 14997160.

It is an arithmetic number, because the mean of its divisors is an integer number (4558952416).

Almost surely, 2^18205815949 is an apocalyptic number.

It is an amenable number.

18205815949 is a deficient number, since it is larger than the sum of its proper divisors (29993715).

18205815949 is an equidigital number, since it uses as much as digits as its factorization.

18205815949 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29993714.

The product of its (nonzero) digits is 1036800, while the sum is 52.

The spelling of 18205815949 in words is "eighteen billion, two hundred five million, eight hundred fifteen thousand, nine hundred forty-nine".