18973645 has 4 divisors (see below), whose sum is σ = 22768380. Its totient is φ = 15178912.

The previous prime is 18973631. The next prime is 18973657. The reversal of 18973645 is 54637981.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54637981 = 139 ⋅393079.

It can be written as a sum of positive squares in 2 ways, for example, as 15139881 + 3833764 = 3891^2 + 1958^2 .

It is a cyclic number.

It is not a de Polignac number, because 18973645 - 2⁷ = 18973517 is a prime.

It is a super-3 number, since 3×18973645³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1897360 + ... + 1897369.

It is an arithmetic number, because the mean of its divisors is an integer number (5692095).

Almost surely, 2^18973645 is an apocalyptic number.

It is an amenable number.

18973645 is a deficient number, since it is larger than the sum of its proper divisors (3794735).

18973645 is an equidigital number, since it uses as much as digits as its factorization.

18973645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3794734.

The product of its digits is 181440, while the sum is 43.

The square root of 18973645 is about 4355.8747686314. The cubic root of 18973645 is about 266.7167293162.

The spelling of 18973645 in words is "eighteen million, nine hundred seventy-three thousand, six hundred forty-five".