20966021 has 4 divisors (see below), whose sum is σ = 20980332. Its totient is φ = 20951712.

The previous prime is 20966017. The next prime is 20966027. The reversal of 20966021 is 12066902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12066902 = 2 ⋅6033451.

It can be written as a sum of positive squares in 2 ways, for example, as 2217121 + 18748900 = 1489^2 + 4330^2 .

It is a cyclic number.

It is not a de Polignac number, because 20966021 - 2² = 20966017 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 (20966027) 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, 4670 + ... + 7983.

It is an arithmetic number, because the mean of its divisors is an integer number (5245083).

Almost surely, 2^20966021 is an apocalyptic number.

It is an amenable number.

20966021 is a deficient number, since it is larger than the sum of its proper divisors (14311).

20966021 is a wasteful number, since it uses less digits than its factorization.

20966021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14310.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 20966021 is about 4578.8667812025. The cubic root of 20966021 is about 275.7435349530.

The spelling of 20966021 in words is "twenty million, nine hundred sixty-six thousand, twenty-one".