18399749 has 2 divisors, whose sum is σ = 18399750. Its totient is φ = 18399748.

The previous prime is 18399737. The next prime is 18399751. The reversal of 18399749 is 94799381.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10660225 + 7739524 = 3265^2 + 2782^2 .

It is an emirp because it is prime and its reverse (94799381) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18399749 is a prime.

Together with 18399751, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 18399697 and 18399706.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18399349) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9199874 + 9199875.

It is an arithmetic number, because the mean of its divisors is an integer number (9199875).

Almost surely, 2^18399749 is an apocalyptic number.

It is an amenable number.

18399749 is a deficient number, since it is larger than the sum of its proper divisors (1).

18399749 is an equidigital number, since it uses as much as digits as its factorization.

18399749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 489888, while the sum is 50.

The square root of 18399749 is about 4289.4928604673. The cubic root of 18399749 is about 264.0000239134. Note that the first 4 decimals are identical.

The spelling of 18399749 in words is "eighteen million, three hundred ninety-nine thousand, seven hundred forty-nine".