21705007 has 2 divisors, whose sum is σ = 21705008. Its totient is φ = 21705006.

The previous prime is 21704999. The next prime is 21705029. The reversal of 21705007 is 70050712.

It is an a-pointer prime, because the next prime (21705029) can be obtained adding 21705007 to its sum of digits (22).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21705007 - 2³ = 21704999 is a prime.

It is a super-2 number, since 2×21705007² = 942214657740098, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21708007) 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, 10852503 + 10852504.

It is an arithmetic number, because the mean of its divisors is an integer number (10852504).

Almost surely, 2^21705007 is an apocalyptic number.

21705007 is a deficient number, since it is larger than the sum of its proper divisors (1).

21705007 is an equidigital number, since it uses as much as digits as its factorization.

21705007 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 490, while the sum is 22.

The square root of 21705007 is about 4658.8632733747. The cubic root of 21705007 is about 278.9458963361.

Adding to 21705007 its reverse (70050712), we get a palindrome (91755719).

The spelling of 21705007 in words is "twenty-one million, seven hundred five thousand, seven".