21780017061120 has 1728 divisors, whose sum is σ = 84926390814720. Its totient is φ = 5331773030400.

The previous prime is 21780017061071. The next prime is 21780017061239. The reversal of 21780017061120 is 2116071008712.

21780017061120 is a `hidden beast` number, since 2 + 1 + 7 + 8 + 0 + 0 + 17 + 0 + 611 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (1728).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 14627277336 + ... + 14627278824.

Almost surely, 2^{21780017061120} is an apocalyptic number.

21780017061120 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 21780017061120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42463195407360).

21780017061120 is an abundant number, since it is smaller than the sum of its proper divisors (63146373753600).

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

21780017061120 is a wasteful number, since it uses less digits than its factorization.

21780017061120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1634 (or 1608 counting only the distinct ones).

The product of its (nonzero) digits is 9408, while the sum is 36.

Adding to 21780017061120 its reverse (2116071008712), we get a palindrome (23896088069832).

The spelling of 21780017061120 in words is "twenty-one trillion, seven hundred eighty billion, seventeen million, sixty-one thousand, one hundred twenty".