21062521 has 2 divisors, whose sum is σ = 21062522. Its totient is φ = 21062520.

The previous prime is 21062519. The next prime is 21062527. The reversal of 21062521 is 12526012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21058921 + 3600 = 4589^2 + 60^2 .

It is a cyclic number.

It is not a de Polignac number, because 21062521 - 2¹ = 21062519 is a prime.

Together with 21062519, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21062527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10531260 + 10531261.

It is an arithmetic number, because the mean of its divisors is an integer number (10531261).

Almost surely, 2^21062521 is an apocalyptic number.

It is an amenable number.

21062521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21062521 is an equidigital number, since it uses as much as digits as its factorization.

21062521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 21062521 is about 4589.3922255567. The cubic root of 21062521 is about 276.1659411330.

Adding to 21062521 its reverse (12526012), we get a palindrome (33588533).

The spelling of 21062521 in words is "twenty-one million, sixty-two thousand, five hundred twenty-one".