20665620 has 36 divisors (see below), whose sum is σ = 62686260. Its totient is φ = 5510784.

The previous prime is 20665577. The next prime is 20665621. The reversal of 20665620 is 2656602.

20665620 is a `hidden beast` number, since 2 + 0 + 6 + 656 + 2 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 11737476 + 8928144 = 3426^2 + 2988^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20665621) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 57225 + ... + 57584.

It is an arithmetic number, because the mean of its divisors is an integer number (1741285).

Almost surely, 2^20665620 is an apocalyptic number.

20665620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20665620 is an abundant number, since it is smaller than the sum of its proper divisors (42020640).

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

20665620 is a wasteful number, since it uses less digits than its factorization.

20665620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114824 (or 114819 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 20665620 is about 4545.9454462191. The cubic root of 20665620 is about 274.4202441807.

The spelling of 20665620 in words is "twenty million, six hundred sixty-five thousand, six hundred twenty".