13900021 has 4 divisors (see below), whose sum is σ = 14107552. Its totient is φ = 13692492.

The previous prime is 13900013. The next prime is 13900043. The reversal of 13900021 is 12000931.

13900021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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.

It is a cyclic number.

It is not a de Polignac number, because 13900021 - 2³ = 13900013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 13899968 and 13900004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13900721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 103665 + ... + 103798.

It is an arithmetic number, because the mean of its divisors is an integer number (3526888).

Almost surely, 2^13900021 is an apocalyptic number.

It is an amenable number.

13900021 is a deficient number, since it is larger than the sum of its proper divisors (207531).

13900021 is an equidigital number, since it uses as much as digits as its factorization.

13900021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207530.

The product of its (nonzero) digits is 54, while the sum is 16.

The square root of 13900021 is about 3728.2731927797. The cubic root of 13900021 is about 240.4391323641.

Adding to 13900021 its reverse (12000931), we get a palindrome (25900952).

The spelling of 13900021 in words is "thirteen million, nine hundred thousand, twenty-one".