20825921 has 2 divisors, whose sum is σ = 20825922. Its totient is φ = 20825920.

The previous prime is 20825891. The next prime is 20825923. The reversal of 20825921 is 12952802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19228225 + 1597696 = 4385^2 + 1264^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20825921 is a prime.

Together with 20825923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20825923) 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, 10412960 + 10412961.

It is an arithmetic number, because the mean of its divisors is an integer number (10412961).

Almost surely, 2^20825921 is an apocalyptic number.

It is an amenable number.

20825921 is a deficient number, since it is larger than the sum of its proper divisors (1).

20825921 is an equidigital number, since it uses as much as digits as its factorization.

20825921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 20825921 is about 4563.5425932054. The cubic root of 20825921 is about 275.1279668897.

The spelling of 20825921 in words is "twenty million, eight hundred twenty-five thousand, nine hundred twenty-one".