20517488640 has 576 divisors, whose sum is σ = 79816726080. Its totient is φ = 4830658560.

The previous prime is 20517488633. The next prime is 20517488647. The reversal of 20517488640 is 4688471502.

It is an interprime number because it is at equal distance from previous prime (20517488633) and next prime (20517488647).

It is a tau number, because it is divible by the number of its divisors (576).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (20517488647) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 37508847 + ... + 37509393.

It is an arithmetic number, because the mean of its divisors is an integer number (138570705).

Almost surely, 2^20517488640 is an apocalyptic number.

20517488640 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 20517488640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39908363040).

20517488640 is an abundant number, since it is smaller than the sum of its proper divisors (59299237440).

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

20517488640 is a wasteful number, since it uses less digits than its factorization.

20517488640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 628 (or 605 counting only the distinct ones).

The product of its (nonzero) digits is 430080, while the sum is 45.

The spelling of 20517488640 in words is "twenty billion, five hundred seventeen million, four hundred eighty-eight thousand, six hundred forty".