21006071 has 2 divisors, whose sum is σ = 21006072. Its totient is φ = 21006070.

The previous prime is 21006053. The next prime is 21006079. The reversal of 21006071 is 17060012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21006071 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21006079) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10503035 + 10503036.

It is an arithmetic number, because the mean of its divisors is an integer number (10503036).

Almost surely, 2^21006071 is an apocalyptic number.

21006071 is a deficient number, since it is larger than the sum of its proper divisors (1).

21006071 is an equidigital number, since it uses as much as digits as its factorization.

21006071 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84, while the sum is 17.

The square root of 21006071 is about 4583.2380474944. The cubic root of 21006071 is about 275.9190014712.

Adding to 21006071 its reverse (17060012), we get a palindrome (38066083).

The spelling of 21006071 in words is "twenty-one million, six thousand, seventy-one".