21070447 has 2 divisors, whose sum is σ = 21070448. Its totient is φ = 21070446.

The previous prime is 21070403. The next prime is 21070477. The reversal of 21070447 is 74407012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21070447 - 2¹⁹ = 20546159 is a prime.

It is equal to p_1334149 and since 21070447 and 1334149 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21070477) 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, 10535223 + 10535224.

It is an arithmetic number, because the mean of its divisors is an integer number (10535224).

Almost surely, 2^21070447 is an apocalyptic number.

21070447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21070447 is an equidigital number, since it uses as much as digits as its factorization.

21070447 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1568, while the sum is 25.

The square root of 21070447 is about 4590.2556573681. The cubic root of 21070447 is about 276.2005779608.

Adding to 21070447 its reverse (74407012), we get a palindrome (95477459).

The spelling of 21070447 in words is "twenty-one million, seventy thousand, four hundred forty-seven".