20657281 has 2 divisors, whose sum is σ = 20657282. Its totient is φ = 20657280.

The previous prime is 20657269. The next prime is 20657293. The reversal of 20657281 is 18275602.

It is the 1856-th star number.

It is a balanced prime because it is at equal distance from previous prime (20657269) and next prime (20657293).

It can be written as a sum of positive squares in only one way, i.e., 20657025 + 256 = 4545^2 + 16^2 .

It is a cyclic number.

It is not a de Polignac number, because 20657281 - 2¹³ = 20649089 is a prime.

It is a super-2 number, since 2×20657281² = 853446516625922, which contains 22 as substring.

It is a Chen prime.

It is equal to p_1309594 and since 20657281 and 1309594 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (20657201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10328640 + 10328641.

It is an arithmetic number, because the mean of its divisors is an integer number (10328641).

Almost surely, 2^20657281 is an apocalyptic number.

It is an amenable number.

20657281 is a deficient number, since it is larger than the sum of its proper divisors (1).

20657281 is an equidigital number, since it uses as much as digits as its factorization.

20657281 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 20657281 is about 4545.0281627290. The cubic root of 20657281 is about 274.3833278225.

The spelling of 20657281 in words is "twenty million, six hundred fifty-seven thousand, two hundred eighty-one".