20981327640 has 384 divisors, whose sum is σ = 79827068160.
Its totient is φ = 4372171776.
The previous prime is 20981327567. The next prime is 20981327663. The reversal of 20981327640 is 4672318902.
It is a super-2 number, since 2×209813276402 (a number of 21 digits) contains 22 as substring.
It is a Harshad number since it is a multiple of its sum of digits (42).
It is a junction number, because it is equal to n+sod(n) for n = 20981327592 and 20981327601.
It is a congruent number.
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, 6342867 + ... + 6346173.
It is an arithmetic number, because the mean of its divisors is an integer number (207882990).
Almost surely, 220981327640 is an apocalyptic number.
20981327640 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 20981327640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39913534080).
20981327640 is an abundant number, since it is smaller than the sum of its proper divisors (58845740520).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
20981327640 is a wasteful number, since it uses less digits than its factorization.
20981327640 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 3431 (or 3420 counting only the distinct ones).
The product of its (nonzero) digits is 145152, while the sum is 42.
The spelling of 20981327640 in words is "twenty billion, nine hundred eighty-one million, three hundred twenty-seven thousand, six hundred forty".