20811321 has 6 divisors (see below), whose sum is σ = 30060810. Its totient is φ = 13874208.

The previous prime is 20811283. The next prime is 20811331. The reversal of 20811321 is 12311802.

It can be written as a sum of positive squares in only one way, i.e., 11594025 + 9217296 = 3405^2 + 3036^2 .

It is not a de Polignac number, because 20811321 - 2⁶ = 20811257 is a prime.

It is a super-2 number, since 2×20811321² = 866222163530082, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20811294 and 20811303.

It is not an unprimeable number, because it can be changed into a prime (20811331) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1156176 + ... + 1156193.

It is an arithmetic number, because the mean of its divisors is an integer number (5010135).

Almost surely, 2^20811321 is an apocalyptic number.

It is an amenable number.

20811321 is a deficient number, since it is larger than the sum of its proper divisors (9249489).

20811321 is a wasteful number, since it uses less digits than its factorization.

20811321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2312375 (or 2312372 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 20811321 is about 4561.9426782896. The cubic root of 20811321 is about 275.0636590918.

The spelling of 20811321 in words is "twenty million, eight hundred eleven thousand, three hundred twenty-one".