20642791680 has 864 divisors, whose sum is σ = 89281920000. Its totient is φ = 4461060096.

The previous prime is 20642791679. The next prime is 20642791711. The reversal of 20642791680 is 8619724602.

It is a happy number.

20642791680 is a `hidden beast` number, since 206 + 427 + 9 + 16 + 8 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (864).

It is a super-2 number, since 2×20642791680² (a number of 21 digits) contains 22 as substring.

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

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 41368071 + ... + 41368569.

Almost surely, 2^20642791680 is an apocalyptic number.

20642791680 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 20642791680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44640960000).

20642791680 is an abundant number, since it is smaller than the sum of its proper divisors (68639128320).

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

20642791680 is an equidigital number, since it uses as much as digits as its factorization.

20642791680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 561 (or 535 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The spelling of 20642791680 in words is "twenty billion, six hundred forty-two million, seven hundred ninety-one thousand, six hundred eighty".