18649 has 4 divisors (see below), whose sum is σ = 19764. Its totient is φ = 17536.

The previous prime is 18637. The next prime is 18661. The reversal of 18649 is 94681.

18649 = T₁₁₀ + T₁₁₁ + T₁₁₂.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 94681 = 73 ⋅1297.

It is an interprime number because it is at equal distance from previous prime (18637) and next prime (18661).

It can be written as a sum of positive squares in 2 ways, for example, as 10000 + 8649 = 100^2 + 93^2 .

It is a cyclic number.

It is not a de Polignac number, because 18649 - 2⁵ = 18617 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 8 and base 12.

It is not an unprimeable number, because it can be changed into a prime (18679) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 532 + ... + 565.

It is an arithmetic number, because the mean of its divisors is an integer number (4941).

2¹⁸⁶⁴⁹ is an apocalyptic number.

18649 is the 112-nd centered triangular number.

It is an amenable number.

18649 is a deficient number, since it is larger than the sum of its proper divisors (1115).

18649 is a wasteful number, since it uses less digits than its factorization.

18649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1114.

The product of its digits is 1728, while the sum is 28.

The square root of 18649 is about 136.5613415283. The cubic root of 18649 is about 26.5186767591.

The spelling of 18649 in words is "eighteen thousand, six hundred forty-nine".