20266861 has 4 divisors (see below), whose sum is σ = 20814652. Its totient is φ = 19719072.

The previous prime is 20266849. The next prime is 20266867. The reversal of 20266861 is 16866202.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16866202 = 2 ⋅8433101.

It can be written as a sum of positive squares in 2 ways, for example, as 7946761 + 12320100 = 2819^2 + 3510^2 .

It is a cyclic number.

It is not a de Polignac number, because 20266861 - 2⁷ = 20266733 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20266867) 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, 273840 + ... + 273913.

It is an arithmetic number, because the mean of its divisors is an integer number (5203663).

Almost surely, 2^20266861 is an apocalyptic number.

It is an amenable number.

20266861 is a deficient number, since it is larger than the sum of its proper divisors (547791).

20266861 is an equidigital number, since it uses as much as digits as its factorization.

20266861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 547790.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 20266861 is about 4501.8730546296. The cubic root of 20266861 is about 272.6437184819.

The spelling of 20266861 in words is "twenty million, two hundred sixty-six thousand, eight hundred sixty-one".