21642307 has 2 divisors, whose sum is σ = 21642308. Its totient is φ = 21642306.

The previous prime is 21642289. The next prime is 21642317. The reversal of 21642307 is 70324612.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21642307 is a prime.

It is not a weakly prime, because it can be changed into another prime (21642317) 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 as a sum of consecutive naturals, namely, 10821153 + 10821154.

It is an arithmetic number, because the mean of its divisors is an integer number (10821154).

Almost surely, 2^21642307 is an apocalyptic number.

21642307 is a deficient number, since it is larger than the sum of its proper divisors (1).

21642307 is an equidigital number, since it uses as much as digits as its factorization.

21642307 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 25.

The square root of 21642307 is about 4652.1292974293. The cubic root of 21642307 is about 278.6770370814.

Adding to 21642307 its reverse (70324612), we get a palindrome (91966919).

The spelling of 21642307 in words is "twenty-one million, six hundred forty-two thousand, three hundred seven".