20811380 has 24 divisors (see below), whose sum is σ = 43953000. Its totient is φ = 8277120.

The previous prime is 20811379. The next prime is 20811391. The reversal of 20811380 is 8311802.

It can be written as a sum of positive squares in 4 ways, for example, as 2390116 + 18421264 = 1546^2 + 4292^2 .

It is a super-2 number, since 2×20811380² = 866227075008800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 746 + ... + 6494.

It is an arithmetic number, because the mean of its divisors is an integer number (1831375).

Almost surely, 2^20811380 is an apocalyptic number.

20811380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20811380 is an abundant number, since it is smaller than the sum of its proper divisors (23141620).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20811380 is a wasteful number, since it uses less digits than its factorization.

20811380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5939 (or 5937 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 23.

The square root of 20811380 is about 4561.9491448283. The cubic root of 20811380 is about 275.0639190263.

The spelling of 20811380 in words is "twenty million, eight hundred eleven thousand, three hundred eighty".