20986897 has 2 divisors, whose sum is σ = 20986898. Its totient is φ = 20986896.

The previous prime is 20986883. The next prime is 20986913. The reversal of 20986897 is 79868902.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18455616 + 2531281 = 4296^2 + 1591^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20986897 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20986897.

It is not a weakly prime, because it can be changed into another prime (20986817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10493448 + 10493449.

It is an arithmetic number, because the mean of its divisors is an integer number (10493449).

Almost surely, 2^20986897 is an apocalyptic number.

It is an amenable number.

20986897 is a deficient number, since it is larger than the sum of its proper divisors (1).

20986897 is an equidigital number, since it uses as much as digits as its factorization.

20986897 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 435456, while the sum is 49.

The square root of 20986897 is about 4581.1458173693. The cubic root of 20986897 is about 275.8350244560.

The spelling of 20986897 in words is "twenty million, nine hundred eighty-six thousand, eight hundred ninety-seven".