20661688320 has 768 divisors, whose sum is σ = 85857408000. Its totient is φ = 4119330816.

The previous prime is 20661688309. The next prime is 20661688321. The reversal of 20661688320 is 2388616602.

It is a tau number, because it is divible by the number of its divisors (768).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20661688321) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 53114686 + ... + 53115074.

It is an arithmetic number, because the mean of its divisors is an integer number (111793500).

Almost surely, 2^20661688320 is an apocalyptic number.

20661688320 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 20661688320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42928704000).

20661688320 is an abundant number, since it is smaller than the sum of its proper divisors (65195719680).

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

20661688320 is a wasteful number, since it uses less digits than its factorization.

20661688320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 458 (or 438 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 42.

The spelling of 20661688320 in words is "twenty billion, six hundred sixty-one million, six hundred eighty-eight thousand, three hundred twenty".