21103437 has 4 divisors (see below), whose sum is σ = 28137920. Its totient is φ = 14068956.

The previous prime is 21103403. The next prime is 21103441. The reversal of 21103437 is 73430112.

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 not a de Polignac number, because 21103437 - 2⁶ = 21103373 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 (21103457) 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, 3517237 + ... + 3517242.

It is an arithmetic number, because the mean of its divisors is an integer number (7034480).

Almost surely, 2^21103437 is an apocalyptic number.

It is an amenable number.

21103437 is a deficient number, since it is larger than the sum of its proper divisors (7034483).

21103437 is an equidigital number, since it uses as much as digits as its factorization.

21103437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7034482.

The product of its (nonzero) digits is 504, while the sum is 21.

The square root of 21103437 is about 4593.8477336542. The cubic root of 21103437 is about 276.3446518814.

Adding to 21103437 its reverse (73430112), we get a palindrome (94533549).

The spelling of 21103437 in words is "twenty-one million, one hundred three thousand, four hundred thirty-seven".