20867521 has 2 divisors, whose sum is σ = 20867522. Its totient is φ = 20867520.

The previous prime is 20867489. The next prime is 20867527. The reversal of 20867521 is 12576802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20349121 + 518400 = 4511^2 + 720^2 .

It is a cyclic number.

It is not a de Polignac number, because 20867521 - 2⁵ = 20867489 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20867527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10433760 + 10433761.

It is an arithmetic number, because the mean of its divisors is an integer number (10433761).

Almost surely, 2^20867521 is an apocalyptic number.

It is an amenable number.

20867521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20867521 is an equidigital number, since it uses as much as digits as its factorization.

20867521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 20867521 is about 4568.0981819571. The cubic root of 20867521 is about 275.3110354024.

The spelling of 20867521 in words is "twenty million, eight hundred sixty-seven thousand, five hundred twenty-one".