21012671 has 2 divisors, whose sum is σ = 21012672. Its totient is φ = 21012670.

The previous prime is 21012661. The next prime is 21012679. The reversal of 21012671 is 17621012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21012671 - 2¹⁰ = 21011647 is a prime.

It is a super-3 number, since 3×21012671³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21012679) 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, 10506335 + 10506336.

It is an arithmetic number, because the mean of its divisors is an integer number (10506336).

Almost surely, 2^21012671 is an apocalyptic number.

21012671 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012671 is an equidigital number, since it uses as much as digits as its factorization.

21012671 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 168, while the sum is 20.

The square root of 21012671 is about 4583.9580059158. The cubic root of 21012671 is about 275.9478958913.

Adding to 21012671 its reverse (17621012), we get a palindrome (38633683).

The spelling of 21012671 in words is "twenty-one million, twelve thousand, six hundred seventy-one".