18043649 has 16 divisors (see below), whose sum is σ = 20168400. Its totient is φ = 16035840.

The previous prime is 18043633. The next prime is 18043657. The reversal of 18043649 is 94634081.

It can be written as a sum of positive squares in 8 ways, for example, as 2496400 + 15547249 = 1580^2 + 3943^2 .

It is a cyclic number.

It is not a de Polignac number, because 18043649 - 2⁴ = 18043633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18043609) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51527 + ... + 51875.

It is an arithmetic number, because the mean of its divisors is an integer number (1260525).

Almost surely, 2^18043649 is an apocalyptic number.

It is an amenable number.

18043649 is a deficient number, since it is larger than the sum of its proper divisors (2124751).

18043649 is a wasteful number, since it uses less digits than its factorization.

18043649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 500.

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 18043649 is about 4247.7816563472. The cubic root of 18043649 is about 262.2858068285.

The spelling of 18043649 in words is "eighteen million, forty-three thousand, six hundred forty-nine".