20661197760 has 672 divisors, whose sum is σ = 84372492672. Its totient is φ = 4543119360.

The previous prime is 20661197701. The next prime is 20661197761. The reversal of 20661197760 is 6779116602.

It is a happy number.

20661197760 is a `hidden beast` number, since 20 + 6 + 611 + 9 + 7 + 7 + 6 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (672).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20661197761) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 65177122 + ... + 65177438.

Almost surely, 2^20661197760 is an apocalyptic number.

20661197760 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 20661197760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42186246336).

20661197760 is an abundant number, since it is smaller than the sum of its proper divisors (63711294912).

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

20661197760 is a wasteful number, since it uses less digits than its factorization.

20661197760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 461 (or 448 counting only the distinct ones).

The product of its (nonzero) digits is 190512, while the sum is 45.

The spelling of 20661197760 in words is "twenty billion, six hundred sixty-one million, one hundred ninety-seven thousand, seven hundred sixty".