21103421 has 4 divisors (see below), whose sum is σ = 21115644. Its totient is φ = 21091200.

The previous prime is 21103403. The next prime is 21103441. The reversal of 21103421 is 12430112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5784025 + 15319396 = 2405^2 + 3914^2 .

It is a cyclic number.

It is not a de Polignac number, because 21103421 - 2¹⁸ = 20841277 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21103396 and 21103405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21103441) 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, 2990 + ... + 7151.

It is an arithmetic number, because the mean of its divisors is an integer number (5278911).

Almost surely, 2^21103421 is an apocalyptic number.

It is an amenable number.

21103421 is a deficient number, since it is larger than the sum of its proper divisors (12223).

21103421 is a wasteful number, since it uses less digits than its factorization.

21103421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12222.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 21103421 is about 4593.8459921943. The cubic root of 21103421 is about 276.3445820426.

Adding to 21103421 its reverse (12430112), we get a palindrome (33533533).

The spelling of 21103421 in words is "twenty-one million, one hundred three thousand, four hundred twenty-one".