20655997 has 2 divisors, whose sum is σ = 20655998. Its totient is φ = 20655996.

The previous prime is 20655991. The next prime is 20656057. The reversal of 20655997 is 79955602.

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., 18844281 + 1811716 = 4341^2 + 1346^2 .

It is a cyclic number.

It is not a de Polignac number, because 20655997 - 2³ = 20655989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20655991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10327998 + 10327999.

It is an arithmetic number, because the mean of its divisors is an integer number (10327999).

Almost surely, 2^20655997 is an apocalyptic number.

It is an amenable number.

20655997 is a deficient number, since it is larger than the sum of its proper divisors (1).

20655997 is an equidigital number, since it uses as much as digits as its factorization.

20655997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 170100, while the sum is 43.

The square root of 20655997 is about 4544.8869072838. The cubic root of 20655997 is about 274.3776427327.

The spelling of 20655997 in words is "twenty million, six hundred fifty-five thousand, nine hundred ninety-seven".