21032521 has 2 divisors, whose sum is σ = 21032522. Its totient is φ = 21032520.

The previous prime is 21032513. The next prime is 21032527. The reversal of 21032521 is 12523012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13220496 + 7812025 = 3636^2 + 2795^2 .

It is a cyclic number.

It is not a de Polignac number, because 21032521 - 2³ = 21032513 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 21032495 and 21032504.

It is not a weakly prime, because it can be changed into another prime (21032527) 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, 10516260 + 10516261.

It is an arithmetic number, because the mean of its divisors is an integer number (10516261).

Almost surely, 2^21032521 is an apocalyptic number.

It is an amenable number.

21032521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21032521 is an equidigital number, since it uses as much as digits as its factorization.

21032521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21032521 is about 4586.1226542691. The cubic root of 21032521 is about 276.0347616022.

Adding to 21032521 its reverse (12523012), we get a palindrome (33555533).

It can be divided in two parts, 2103 and 2521, that added together give a square (4624 = 68²).

The spelling of 21032521 in words is "twenty-one million, thirty-two thousand, five hundred twenty-one".