18336991 has 2 divisors, whose sum is σ = 18336992. Its totient is φ = 18336990.

The previous prime is 18336973. The next prime is 18337009. The reversal of 18336991 is 19963381.

It is a balanced prime because it is at equal distance from previous prime (18336973) and next prime (18337009).

It is an emirp because it is prime and its reverse (19963381) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18336991 - 2¹³ = 18328799 is a prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18336971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9168495 + 9168496.

It is an arithmetic number, because the mean of its divisors is an integer number (9168496).

Almost surely, 2^18336991 is an apocalyptic number.

18336991 is a deficient number, since it is larger than the sum of its proper divisors (1).

18336991 is an equidigital number, since it uses as much as digits as its factorization.

18336991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34992, while the sum is 40.

The square root of 18336991 is about 4282.1712950325. The cubic root of 18336991 is about 263.6995309346.

The spelling of 18336991 in words is "eighteen million, three hundred thirty-six thousand, nine hundred ninety-one".