20659997 has 2 divisors, whose sum is σ = 20659998. Its totient is φ = 20659996.

The previous prime is 20659943. The next prime is 20659999. The reversal of 20659997 is 79995602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17884441 + 2775556 = 4229^2 + 1666^2 .

It is a cyclic number.

It is not a de Polignac number, because 20659997 - 2⁸ = 20659741 is a prime.

Together with 20659999, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20659999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10329998 + 10329999.

It is an arithmetic number, because the mean of its divisors is an integer number (10329999).

Almost surely, 2^20659997 is an apocalyptic number.

It is an amenable number.

20659997 is a deficient number, since it is larger than the sum of its proper divisors (1).

20659997 is an equidigital number, since it uses as much as digits as its factorization.

20659997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 306180, while the sum is 47.

The square root of 20659997 is about 4545.3269409362. The cubic root of 20659997 is about 274.3953525167.

The spelling of 20659997 in words is "twenty million, six hundred fifty-nine thousand, nine hundred ninety-seven".