18645421 has 4 divisors (see below), whose sum is σ = 18753372. Its totient is φ = 18537472.

The previous prime is 18645401. The next prime is 18645439. The reversal of 18645421 is 12454681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12454681 = 37 ⋅336613.

It can be written as a sum of positive squares in 2 ways, for example, as 15444900 + 3200521 = 3930^2 + 1789^2 .

It is a cyclic number.

It is not a de Polignac number, because 18645421 - 2⁷ = 18645293 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18645401) by changing a digit.

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, 53716 + ... + 54061.

It is an arithmetic number, because the mean of its divisors is an integer number (4688343).

Almost surely, 2^18645421 is an apocalyptic number.

It is an amenable number.

18645421 is a deficient number, since it is larger than the sum of its proper divisors (107951).

18645421 is a wasteful number, since it uses less digits than its factorization.

18645421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107950.

The product of its digits is 7680, while the sum is 31.

The square root of 18645421 is about 4318.0343907848. The cubic root of 18645421 is about 265.1698021742.

The spelling of 18645421 in words is "eighteen million, six hundred forty-five thousand, four hundred twenty-one".