20667281 has 2 divisors, whose sum is σ = 20667282. Its totient is φ = 20667280.

The previous prime is 20667277. The next prime is 20667293. The reversal of 20667281 is 18276602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19492225 + 1175056 = 4415^2 + 1084^2 .

It is a cyclic number.

It is not a de Polignac number, because 20667281 - 2² = 20667277 is a prime.

It is a super-2 number, since 2×20667281² = 854273007865922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20667211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10333640 + 10333641.

It is an arithmetic number, because the mean of its divisors is an integer number (10333641).

Almost surely, 2^20667281 is an apocalyptic number.

It is an amenable number.

20667281 is a deficient number, since it is larger than the sum of its proper divisors (1).

20667281 is an equidigital number, since it uses as much as digits as its factorization.

20667281 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 20667281 is about 4546.1281328181. The cubic root of 20667281 is about 274.4275961630.

The spelling of 20667281 in words is "twenty million, six hundred sixty-seven thousand, two hundred eighty-one".