20643240000 has 140 divisors (see below), whose sum is σ = 68251764944. Its totient is φ = 5504832000.

The previous prime is 20643239999. The next prime is 20643240043. The reversal of 20643240000 is 4234602.

It is a super-2 number, since 2×20643240000² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 33987 + ... + 206013.

Almost surely, 2^20643240000 is an apocalyptic number.

20643240000 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 20643240000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34125882472).

20643240000 is an abundant number, since it is smaller than the sum of its proper divisors (47608524944).

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

20643240000 is an equidigital number, since it uses as much as digits as its factorization.

20643240000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172062 (or 172037 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 21.

Adding to 20643240000 its reverse (4234602), we get a palindrome (20647474602).

The spelling of 20643240000 in words is "twenty billion, six hundred forty-three million, two hundred forty thousand".