20960821 has 4 divisors (see below), whose sum is σ = 23955232. Its totient is φ = 17966412.

The previous prime is 20960803. The next prime is 20960831. The reversal of 20960821 is 12806902.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12806902 = 2 ⋅6403451.

It is a cyclic number.

It is not a de Polignac number, because 20960821 - 2⁵ = 20960789 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20960821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20960831) 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, 1497195 + ... + 1497208.

It is an arithmetic number, because the mean of its divisors is an integer number (5988808).

Almost surely, 2^20960821 is an apocalyptic number.

It is an amenable number.

20960821 is a deficient number, since it is larger than the sum of its proper divisors (2994411).

20960821 is an equidigital number, since it uses as much as digits as its factorization.

20960821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2994410.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 20960821 is about 4578.2989199046. The cubic root of 20960821 is about 275.7207363981.

The spelling of 20960821 in words is "twenty million, nine hundred sixty thousand, eight hundred twenty-one".