20643851140 has 72 divisors (see below), whose sum is σ = 47717734680. Its totient is φ = 7496417280.

The previous prime is 20643851119. The next prime is 20643851141. The reversal of 20643851140 is 4115834602.

It can be written as a sum of positive squares in 4 ways, for example, as 3892761664 + 16751089476 = 62392^2 + 129426^2 .

It is a junction number, because it is equal to n+sod(n) for n = 20643851096 and 20643851105.

It is not an unprimeable number, because it can be changed into a prime (20643851141) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1855434 + ... + 1866526.

It is an arithmetic number, because the mean of its divisors is an integer number (662746315).

Almost surely, 2^20643851140 is an apocalyptic number.

20643851140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20643851140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23858867340).

20643851140 is an abundant number, since it is smaller than the sum of its proper divisors (27073883540).

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

20643851140 is a wasteful number, since it uses less digits than its factorization.

20643851140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11893 (or 11880 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 34.

The spelling of 20643851140 in words is "twenty billion, six hundred forty-three million, eight hundred fifty-one thousand, one hundred forty".