18438649 has 2 divisors, whose sum is σ = 18438650. Its totient is φ = 18438648.

The previous prime is 18438619. The next prime is 18438689. The reversal of 18438649 is 94683481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18003049 + 435600 = 4243^2 + 660^2 .

It is a cyclic number.

It is not a de Polignac number, because 18438649 - 2¹⁹ = 17914361 is a prime.

It is not a weakly prime, because it can be changed into another prime (18438619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9219324 + 9219325.

It is an arithmetic number, because the mean of its divisors is an integer number (9219325).

Almost surely, 2^18438649 is an apocalyptic number.

It is an amenable number.

18438649 is a deficient number, since it is larger than the sum of its proper divisors (1).

18438649 is an equidigital number, since it uses as much as digits as its factorization.

18438649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 165888, while the sum is 43.

The square root of 18438649 is about 4294.0248019777. The cubic root of 18438649 is about 264.1859389899.

The spelling of 18438649 in words is "eighteen million, four hundred thirty-eight thousand, six hundred forty-nine".