21390007 has 2 divisors, whose sum is σ = 21390008. Its totient is φ = 21390006.

The previous prime is 21389999. The next prime is 21390011. The reversal of 21390007 is 70009312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21390007 - 2³ = 21389999 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21390007.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21397007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10695003 + 10695004.

It is an arithmetic number, because the mean of its divisors is an integer number (10695004).

Almost surely, 2^21390007 is an apocalyptic number.

21390007 is a deficient number, since it is larger than the sum of its proper divisors (1).

21390007 is an equidigital number, since it uses as much as digits as its factorization.

21390007 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 378, while the sum is 22.

The square root of 21390007 is about 4624.9331887066. The cubic root of 21390007 is about 277.5898883651.

Adding to 21390007 its reverse (70009312), we get a palindrome (91399319).

The spelling of 21390007 in words is "twenty-one million, three hundred ninety thousand, seven".