18487999 has 4 divisors (see below), whose sum is σ = 18537160. Its totient is φ = 18438840.

The previous prime is 18487951. The next prime is 18488011. The reversal of 18487999 is 99978481.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99978481 = 179 ⋅558539.

It is a cyclic number.

It is not a de Polignac number, because 18487999 - 2⁹ = 18487487 is a prime.

It is a super-2 number, since 2×18487999² = 683612214048002, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18487919) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24012 + ... + 24769.

It is an arithmetic number, because the mean of its divisors is an integer number (4634290).

Almost surely, 2^18487999 is an apocalyptic number.

18487999 is a deficient number, since it is larger than the sum of its proper divisors (49161).

18487999 is an equidigital number, since it uses as much as digits as its factorization.

18487999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49160.

The product of its digits is 1306368, while the sum is 55.

The square root of 18487999 is about 4299.7673192860. The cubic root of 18487999 is about 264.4214219313.

The spelling of 18487999 in words is "eighteen million, four hundred eighty-seven thousand, nine hundred ninety-nine".