20811284 has 12 divisors (see below), whose sum is σ = 39221364. Its totient is φ = 9605184.

The previous prime is 20811283. The next prime is 20811331. The reversal of 20811284 is 48211802.

It can be written as a sum of positive squares in 2 ways, for example, as 9060100 + 11751184 = 3010^2 + 3428^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20811283) 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, 200057 + ... + 200160.

It is an arithmetic number, because the mean of its divisors is an integer number (3268447).

Almost surely, 2^20811284 is an apocalyptic number.

It is an amenable number.

20811284 is a deficient number, since it is larger than the sum of its proper divisors (18410080).

20811284 is a wasteful number, since it uses less digits than its factorization.

20811284 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 400234 (or 400232 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 26.

The square root of 20811284 is about 4561.9386229979. The cubic root of 20811284 is about 275.0634960818.

The spelling of 20811284 in words is "twenty million, eight hundred eleven thousand, two hundred eighty-four".