18705021 has 16 divisors (see below), whose sum is σ = 25515648. Its totient is φ = 12185600.

The previous prime is 18705019. The next prime is 18705023. The reversal of 18705021 is 12050781.

It is an interprime number because it is at equal distance from previous prime (18705019) and next prime (18705023).

It is a cyclic number.

It is not a de Polignac number, because 18705021 - 2¹ = 18705019 is a prime.

It is a super-2 number, since 2×18705021² = 699755621220882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 18704982 and 18705000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18705023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28861 + ... + 29501.

It is an arithmetic number, because the mean of its divisors is an integer number (1594728).

Almost surely, 2^18705021 is an apocalyptic number.

It is an amenable number.

18705021 is a deficient number, since it is larger than the sum of its proper divisors (6810627).

18705021 is a wasteful number, since it uses less digits than its factorization.

18705021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 852.

The product of its (nonzero) digits is 560, while the sum is 24.

The square root of 18705021 is about 4324.9301728467. The cubic root of 18705021 is about 265.4520396698.

The spelling of 18705021 in words is "eighteen million, seven hundred five thousand, twenty-one".