20321657 has 2 divisors, whose sum is σ = 20321658. Its totient is φ = 20321656.

The previous prime is 20321641. The next prime is 20321669. The reversal of 20321657 is 75612302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20241001 + 80656 = 4499^2 + 284^2 .

It is a cyclic number.

It is not a de Polignac number, because 20321657 - 2⁴ = 20321641 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20321617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10160828 + 10160829.

It is an arithmetic number, because the mean of its divisors is an integer number (10160829).

Almost surely, 2^20321657 is an apocalyptic number.

It is an amenable number.

20321657 is a deficient number, since it is larger than the sum of its proper divisors (1).

20321657 is an equidigital number, since it uses as much as digits as its factorization.

20321657 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2520, while the sum is 26.

The square root of 20321657 is about 4507.9548578041. The cubic root of 20321657 is about 272.8892151580.

Adding to 20321657 its reverse (75612302), we get a palindrome (95933959).

The spelling of 20321657 in words is "twenty million, three hundred twenty-one thousand, six hundred fifty-seven".