21124707 has 4 divisors (see below), whose sum is σ = 28166280. Its totient is φ = 14083136.

The previous prime is 21124703. The next prime is 21124709. The reversal of 21124707 is 70742112.

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

It is a cyclic number.

It is not a de Polignac number, because 21124707 - 2² = 21124703 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21124703) 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, 3520782 + ... + 3520787.

It is an arithmetic number, because the mean of its divisors is an integer number (7041570).

Almost surely, 2^21124707 is an apocalyptic number.

21124707 is a deficient number, since it is larger than the sum of its proper divisors (7041573).

21124707 is an equidigital number, since it uses as much as digits as its factorization.

21124707 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7041572.

The product of its (nonzero) digits is 784, while the sum is 24.

The square root of 21124707 is about 4596.1622034041. The cubic root of 21124707 is about 276.4374626259.

Adding to 21124707 its reverse (70742112), we get a palindrome (91866819).

The spelling of 21124707 in words is "twenty-one million, one hundred twenty-four thousand, seven hundred seven".