13800021 has 4 divisors (see below), whose sum is σ = 18400032. Its totient is φ = 9200012.

The previous prime is 13800019. The next prime is 13800049. The reversal of 13800021 is 12000831.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12000831 = 3 ⋅4000277.

It is a cyclic number.

It is not a de Polignac number, because 13800021 - 2¹ = 13800019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13800071) 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, 2300001 + ... + 2300006.

It is an arithmetic number, because the mean of its divisors is an integer number (4600008).

Almost surely, 2^13800021 is an apocalyptic number.

It is an amenable number.

13800021 is a deficient number, since it is larger than the sum of its proper divisors (4600011).

13800021 is an equidigital number, since it uses as much as digits as its factorization.

13800021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4600010.

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 13800021 is about 3714.8379507053. The cubic root of 13800021 is about 239.8611523266.

Adding to 13800021 its reverse (12000831), we get a palindrome (25800852).

The spelling of 13800021 in words is "thirteen million, eight hundred thousand, twenty-one".