20661311440 has 240 divisors, whose sum is σ = 60962348160. Its totient is φ = 6374016000.

The previous prime is 20661311413. The next prime is 20661311441. The reversal of 20661311440 is 4411316602.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 20661311399 and 20661311408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20661311441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 6842251 + ... + 6845269.

It is an arithmetic number, because the mean of its divisors is an integer number (254009784).

Almost surely, 2^20661311440 is an apocalyptic number.

20661311440 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 20661311440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30481174080).

20661311440 is an abundant number, since it is smaller than the sum of its proper divisors (40301036720).

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

20661311440 is a wasteful number, since it uses less digits than its factorization.

20661311440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3162 (or 3145 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 28.

The spelling of 20661311440 in words is "twenty billion, six hundred sixty-one million, three hundred eleven thousand, four hundred forty".