18087021 has 6 divisors (see below), whose sum is σ = 26125710. Its totient is φ = 12058008.

The previous prime is 18087019. The next prime is 18087023. The reversal of 18087021 is 12078081.

It is an interprime number because it is at equal distance from previous prime (18087019) and next prime (18087023).

It can be written as a sum of positive squares in only one way, i.e., 10634121 + 7452900 = 3261^2 + 2730^2 .

It is not a de Polignac number, because 18087021 - 2¹ = 18087019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18087023) 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, 1004826 + ... + 1004843.

It is an arithmetic number, because the mean of its divisors is an integer number (4354285).

Almost surely, 2^18087021 is an apocalyptic number.

It is an amenable number.

18087021 is a deficient number, since it is larger than the sum of its proper divisors (8038689).

18087021 is a wasteful number, since it uses less digits than its factorization.

18087021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2009675 (or 2009672 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 27.

The square root of 18087021 is about 4252.8838451103. The cubic root of 18087021 is about 262.4957931299.

The spelling of 18087021 in words is "eighteen million, eighty-seven thousand, twenty-one".