20969281 has 2 divisors, whose sum is σ = 20969282. Its totient is φ = 20969280.

The previous prime is 20969239. The next prime is 20969303. The reversal of 20969281 is 18296902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11458225 + 9511056 = 3385^2 + 3084^2 .

It is a cyclic number.

It is not a de Polignac number, because 20969281 - 2⁷ = 20969153 is a prime.

It is a super-2 number, since 2×20969281² = 879421491313922, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20969281.

It is not a weakly prime, because it can be changed into another prime (20969231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10484640 + 10484641.

It is an arithmetic number, because the mean of its divisors is an integer number (10484641).

Almost surely, 2^20969281 is an apocalyptic number.

It is an amenable number.

20969281 is a deficient number, since it is larger than the sum of its proper divisors (1).

20969281 is an equidigital number, since it uses as much as digits as its factorization.

20969281 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 20969281 is about 4579.2227506423. Note that the first 3 decimals coincide. The cubic root of 20969281 is about 275.7578259707.

The spelling of 20969281 in words is "twenty million, nine hundred sixty-nine thousand, two hundred eighty-one".