20661751220 has 96 divisors (see below), whose sum is σ = 49075891200. Its totient is φ = 7238067200.

The previous prime is 20661751217. The next prime is 20661751247. The reversal of 20661751220 is 2215716602.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3052640 + ... + 3059400.

It is an arithmetic number, because the mean of its divisors is an integer number (511207200).

Almost surely, 2^20661751220 is an apocalyptic number.

20661751220 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 20661751220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24537945600).

20661751220 is an abundant number, since it is smaller than the sum of its proper divisors (28414139980).

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

20661751220 is a wasteful number, since it uses less digits than its factorization.

20661751220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7289 (or 7287 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 32.

The spelling of 20661751220 in words is "twenty billion, six hundred sixty-one million, seven hundred fifty-one thousand, two hundred twenty".