20640821760 has 1200 divisors, whose sum is σ = 86984789760. Its totient is φ = 4658135040.

The previous prime is 20640821753. The next prime is 20640821767. The reversal of 20640821760 is 6712804602.

20640821760 is a `hidden beast` number, since 2 + 0 + 640 + 8 + 2 + 1 + 7 + 6 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (20640821753) and next prime (20640821767).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (20640821767) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 665832945 + ... + 665832975.

Almost surely, 2^20640821760 is an apocalyptic number.

20640821760 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 20640821760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43492394880).

20640821760 is an abundant number, since it is smaller than the sum of its proper divisors (66343968000).

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

20640821760 is a wasteful number, since it uses less digits than its factorization.

20640821760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111 (or 73 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

The spelling of 20640821760 in words is "twenty billion, six hundred forty million, eight hundred twenty-one thousand, seven hundred sixty".