18738421 has 8 divisors (see below), whose sum is σ = 20310584. Its totient is φ = 17184960.

The previous prime is 18738373. The next prime is 18738439. The reversal of 18738421 is 12483781.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 505521 + 18232900 = 711^2 + 4270^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18738421 - 2¹⁵ = 18705653 is a prime.

It is a super-2 number, since 2×18738421² = 702256843146482, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18738121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2550 + ... + 6631.

It is an arithmetic number, because the mean of its divisors is an integer number (2538823).

Almost surely, 2^18738421 is an apocalyptic number.

It is an amenable number.

18738421 is a deficient number, since it is larger than the sum of its proper divisors (1572163).

18738421 is a wasteful number, since it uses less digits than its factorization.

18738421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9351.

The product of its digits is 10752, while the sum is 34.

The square root of 18738421 is about 4328.7897846858. The cubic root of 18738421 is about 265.6099442631.

The spelling of 18738421 in words is "eighteen million, seven hundred thirty-eight thousand, four hundred twenty-one".