20287997 has 2 divisors, whose sum is σ = 20287998. Its totient is φ = 20287996.

The previous prime is 20287961. The next prime is 20287999. The reversal of 20287997 is 79978202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11930116 + 8357881 = 3454^2 + 2891^2 .

It is a cyclic number.

It is not a de Polignac number, because 20287997 - 2⁸ = 20287741 is a prime.

Together with 20287999, 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 (20287999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10143998 + 10143999.

It is an arithmetic number, because the mean of its divisors is an integer number (10143999).

Almost surely, 2^20287997 is an apocalyptic number.

It is an amenable number.

20287997 is a deficient number, since it is larger than the sum of its proper divisors (1).

20287997 is an equidigital number, since it uses as much as digits as its factorization.

20287997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 127008, while the sum is 44.

The square root of 20287997 is about 4504.2199102619. The cubic root of 20287997 is about 272.7384642108.

The spelling of 20287997 in words is "twenty million, two hundred eighty-seven thousand, nine hundred ninety-seven".