20806420 has 24 divisors (see below), whose sum is σ = 44188200. Its totient is φ = 8228352.

The previous prime is 20806417. The next prime is 20806433. The reversal of 20806420 is 2460802.

It can be written as a sum of positive squares in 4 ways, for example, as 4822416 + 15984004 = 2196^2 + 3998^2 .

It is a super-2 number, since 2×20806420² = 865814226432800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20806391 and 20806400.

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, 4065 + ... + 7624.

It is an arithmetic number, because the mean of its divisors is an integer number (1841175).

Almost surely, 2^20806420 is an apocalyptic number.

20806420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20806420 is an abundant number, since it is smaller than the sum of its proper divisors (23381780).

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

20806420 is a wasteful number, since it uses less digits than its factorization.

20806420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11787 (or 11785 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 20806420 is about 4561.4054851548. The cubic root of 20806420 is about 275.0420651905.

The spelling of 20806420 in words is "twenty million, eight hundred six thousand, four hundred twenty".