21242307 has 4 divisors (see below), whose sum is σ = 28323080. Its totient is φ = 14161536.

The previous prime is 21242237. The next prime is 21242339. The reversal of 21242307 is 70324212.

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

It is not a de Polignac number, because 21242307 - 2¹² = 21238211 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21242357) 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, 3540382 + ... + 3540387.

It is an arithmetic number, because the mean of its divisors is an integer number (7080770).

Almost surely, 2^21242307 is an apocalyptic number.

21242307 is a deficient number, since it is larger than the sum of its proper divisors (7080773).

21242307 is an equidigital number, since it uses as much as digits as its factorization.

21242307 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7080772.

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 21242307 is about 4608.9377301066. The cubic root of 21242307 is about 276.9494840262.

Adding to 21242307 its reverse (70324212), we get a palindrome (91566519).

The spelling of 21242307 in words is "twenty-one million, two hundred forty-two thousand, three hundred seven".