20897477 has 2 divisors, whose sum is σ = 20897478. Its totient is φ = 20897476.

The previous prime is 20897431. The next prime is 20897479. The reversal of 20897477 is 77479802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20666116 + 231361 = 4546^2 + 481^2 .

It is a cyclic number.

It is not a de Polignac number, because 20897477 - 2⁸ = 20897221 is a prime.

Together with 20897479, it forms a pair of twin primes.

It is a Chen prime.

It is a zygodrome in base 3.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20897479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10448738 + 10448739.

It is an arithmetic number, because the mean of its divisors is an integer number (10448739).

Almost surely, 2^20897477 is an apocalyptic number.

It is an amenable number.

20897477 is a deficient number, since it is larger than the sum of its proper divisors (1).

20897477 is an equidigital number, since it uses as much as digits as its factorization.

20897477 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 197568, while the sum is 44.

The square root of 20897477 is about 4571.3758322851. The cubic root of 20897477 is about 275.4427117067.

The spelling of 20897477 in words is "twenty million, eight hundred ninety-seven thousand, four hundred seventy-seven".