21779488397988 has 192 divisors, whose sum is σ = 60178384896000. Its totient is φ = 6792486076800.

The previous prime is 21779488397981. The next prime is 21779488398029. The reversal of 21779488397988 is 88979388497712.

21779488397988 is a `hidden beast` number, since 2 + 1 + 7 + 7 + 9 + 488 + 39 + 7 + 98 + 8 = 666.

It is a super-2 number, since 2×21779488397988² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21779488397898 and 21779488397907.

It is not an unprimeable number, because it can be changed into a prime (21779488397981) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 54278658 + ... + 54678438.

It is an arithmetic number, because the mean of its divisors is an integer number (313429088000).

Almost surely, 2^{21779488397988} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21779488397988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30089192448000).

21779488397988 is an abundant number, since it is smaller than the sum of its proper divisors (38398896498012).

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

21779488397988 is a wasteful number, since it uses less digits than its factorization.

21779488397988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 400143 (or 400135 counting only the distinct ones).

The product of its digits is 24580620288, while the sum is 90.

The spelling of 21779488397988 in words is "twenty-one trillion, seven hundred seventy-nine billion, four hundred eighty-eight million, three hundred ninety-seven thousand, nine hundred eighty-eight".