21103507 has 4 divisors (see below), whose sum is σ = 21370720. Its totient is φ = 20836296.

The previous prime is 21103501. The next prime is 21103513. The reversal of 21103507 is 70530112.

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

It is an interprime number because it is at equal distance from previous prime (21103501) and next prime (21103513).

It is a cyclic number.

It is not a de Polignac number, because 21103507 - 2¹¹ = 21101459 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21103501) 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, 133488 + ... + 133645.

It is an arithmetic number, because the mean of its divisors is an integer number (5342680).

Almost surely, 2^21103507 is an apocalyptic number.

21103507 is a deficient number, since it is larger than the sum of its proper divisors (267213).

21103507 is an equidigital number, since it uses as much as digits as its factorization.

21103507 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267212.

The product of its (nonzero) digits is 210, while the sum is 19.

The square root of 21103507 is about 4593.8553525334. The cubic root of 21103507 is about 276.3449574257.

Adding to 21103507 its reverse (70530112), we get a palindrome (91633619).

The spelling of 21103507 in words is "twenty-one million, one hundred three thousand, five hundred seven".