20808497 has 2 divisors, whose sum is σ = 20808498. Its totient is φ = 20808496.

The previous prime is 20808481. The next prime is 20808499. The reversal of 20808497 is 79480802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20802721 + 5776 = 4561^2 + 76^2 .

It is a cyclic number.

It is not a de Polignac number, because 20808497 - 2⁴ = 20808481 is a prime.

Together with 20808499, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20808497.

It is not a weakly prime, because it can be changed into another prime (20808499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10404248 + 10404249.

It is an arithmetic number, because the mean of its divisors is an integer number (10404249).

Almost surely, 2^20808497 is an apocalyptic number.

It is an amenable number.

20808497 is a deficient number, since it is larger than the sum of its proper divisors (1).

20808497 is an equidigital number, since it uses as much as digits as its factorization.

20808497 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 20808497 is about 4561.6331505284. The cubic root of 20808497 is about 275.0512169069.

The spelling of 20808497 in words is "twenty million, eight hundred eight thousand, four hundred ninety-seven".