20766281 has 4 divisors (see below), whose sum is σ = 20999700. Its totient is φ = 20532864.

The previous prime is 20766271. The next prime is 20766313. The reversal of 20766281 is 18266702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18266702 = 2 ⋅9133351.

It can be written as a sum of positive squares in 2 ways, for example, as 1229881 + 19536400 = 1109^2 + 4420^2 .

It is a cyclic number.

It is not a de Polignac number, because 20766281 - 2¹⁸ = 20504137 is a prime.

It is a super-2 number, since 2×20766281² = 862476853141922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20766211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 116576 + ... + 116753.

It is an arithmetic number, because the mean of its divisors is an integer number (5249925).

Almost surely, 2^20766281 is an apocalyptic number.

It is an amenable number.

20766281 is a deficient number, since it is larger than the sum of its proper divisors (233419).

20766281 is an equidigital number, since it uses as much as digits as its factorization.

20766281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 233418.

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

The square root of 20766281 is about 4557.0035110805. The cubic root of 20766281 is about 274.8650842340.

Subtracting from 20766281 its sum of digits (32), we obtain a square (20766249 = 4557²).

The spelling of 20766281 in words is "twenty million, seven hundred sixty-six thousand, two hundred eighty-one".