20872821 has 8 divisors (see below), whose sum is σ = 29467584. Its totient is φ = 13096640.

The previous prime is 20872807. The next prime is 20872853. The reversal of 20872821 is 12827802.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20872821 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20872861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 204585 + ... + 204686.

It is an arithmetic number, because the mean of its divisors is an integer number (3683448).

Almost surely, 2^20872821 is an apocalyptic number.

It is an amenable number.

20872821 is a deficient number, since it is larger than the sum of its proper divisors (8594763).

20872821 is a wasteful number, since it uses less digits than its factorization.

20872821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 409291.

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 20872821 is about 4568.6782552506. The cubic root of 20872821 is about 275.3343415564.

The spelling of 20872821 in words is "twenty million, eight hundred seventy-two thousand, eight hundred twenty-one".