21713207 has 2 divisors, whose sum is σ = 21713208. Its totient is φ = 21713206.

The previous prime is 21713203. The next prime is 21713227. The reversal of 21713207 is 70231712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21713207 - 2² = 21713203 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21713203) 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, 10856603 + 10856604.

It is an arithmetic number, because the mean of its divisors is an integer number (10856604).

Almost surely, 2^21713207 is an apocalyptic number.

21713207 is a deficient number, since it is larger than the sum of its proper divisors (1).

21713207 is an equidigital number, since it uses as much as digits as its factorization.

21713207 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 588, while the sum is 23.

The square root of 21713207 is about 4659.7432332694. The cubic root of 21713207 is about 278.9810198502.

Adding to 21713207 its reverse (70231712), we get a palindrome (91944919).

The spelling of 21713207 in words is "twenty-one million, seven hundred thirteen thousand, two hundred seven".