20811620 has 12 divisors (see below), whose sum is σ = 43704444. Its totient is φ = 8324640.

The previous prime is 20811611. The next prime is 20811653. The reversal of 20811620 is 2611802.

It can be written as a sum of positive squares in 2 ways, for example, as 13957696 + 6853924 = 3736^2 + 2618^2 .

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 1040581 = 20811620 / (2 + 0 + 8 + 1 + 1 + 6 + 2 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 20811592 and 20811601.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 520271 + ... + 520310.

It is an arithmetic number, because the mean of its divisors is an integer number (3642037).

Almost surely, 2^20811620 is an apocalyptic number.

20811620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20811620 is an abundant number, since it is smaller than the sum of its proper divisors (22892824).

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

20811620 is a wasteful number, since it uses less digits than its factorization.

20811620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1040590 (or 1040588 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 20811620 is about 4561.9754492983. The cubic root of 20811620 is about 275.0649763819.

The spelling of 20811620 in words is "twenty million, eight hundred eleven thousand, six hundred twenty".