20501861 has 2 divisors, whose sum is σ = 20501862. Its totient is φ = 20501860.

The previous prime is 20501839. The next prime is 20501867. The reversal of 20501861 is 16810502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20079361 + 422500 = 4481^2 + 650^2 .

It is a cyclic number.

It is not a de Polignac number, because 20501861 - 2⁶ = 20501797 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20501867) 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, 10250930 + 10250931.

It is an arithmetic number, because the mean of its divisors is an integer number (10250931).

Almost surely, 2^20501861 is an apocalyptic number.

It is an amenable number.

20501861 is a deficient number, since it is larger than the sum of its proper divisors (1).

20501861 is an equidigital number, since it uses as much as digits as its factorization.

20501861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 20501861 is about 4527.8980774748. The cubic root of 20501861 is about 273.6934652475.

The spelling of 20501861 in words is "twenty million, five hundred one thousand, eight hundred sixty-one".