18987273 has 6 divisors (see below), whose sum is σ = 27426074. Its totient is φ = 12658176.

The previous prime is 18987263. The next prime is 18987299. The reversal of 18987273 is 37278981.

It can be written as a sum of positive squares in only one way, i.e., 14837904 + 4149369 = 3852^2 + 2037^2 .

It is not a de Polignac number, because 18987273 - 2¹⁰ = 18986249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18987233) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1054840 + ... + 1054857.

Almost surely, 2^18987273 is an apocalyptic number.

It is an amenable number.

18987273 is a deficient number, since it is larger than the sum of its proper divisors (8438801).

18987273 is a wasteful number, since it uses less digits than its factorization.

18987273 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2109703 (or 2109700 counting only the distinct ones).

The product of its digits is 169344, while the sum is 45.

The square root of 18987273 is about 4357.4388119628. The cubic root of 18987273 is about 266.7805713049.

The spelling of 18987273 in words is "eighteen million, nine hundred eighty-seven thousand, two hundred seventy-three".