20643620 has 24 divisors (see below), whose sum is σ = 44064888. Its totient is φ = 8121600.

The previous prime is 20643611. The next prime is 20643641. The reversal of 20643620 is 2634602.

It can be written as a sum of positive squares in 4 ways, for example, as 357604 + 20286016 = 598^2 + 4504^2 .

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, 7241 + ... + 9680.

It is an arithmetic number, because the mean of its divisors is an integer number (1836037).

Almost surely, 2^20643620 is an apocalyptic number.

20643620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20643620 is an abundant number, since it is smaller than the sum of its proper divisors (23421268).

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

20643620 is a wasteful number, since it uses less digits than its factorization.

20643620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16991 (or 16989 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 20643620 is about 4543.5250632081. The cubic root of 20643620 is about 274.3228297472.

The spelling of 20643620 in words is "twenty million, six hundred forty-three thousand, six hundred twenty".