20808761 has 2 divisors, whose sum is σ = 20808762. Its totient is φ = 20808760.

The previous prime is 20808737. The next prime is 20808779. The reversal of 20808761 is 16780802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13213225 + 7595536 = 3635^2 + 2756^2 .

It is a cyclic number.

It is not a de Polignac number, because 20808761 - 2¹⁰ = 20807737 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20808461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10404380 + 10404381.

It is an arithmetic number, because the mean of its divisors is an integer number (10404381).

Almost surely, 2^20808761 is an apocalyptic number.

It is an amenable number.

20808761 is a deficient number, since it is larger than the sum of its proper divisors (1).

20808761 is an equidigital number, since it uses as much as digits as its factorization.

20808761 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 20808761 is about 4561.6620874414. The cubic root of 20808761 is about 275.0523801050.

The spelling of 20808761 in words is "twenty million, eight hundred eight thousand, seven hundred sixty-one".