19981578240 has 624 divisors, whose sum is σ = 77281102080. Its totient is φ = 4742184960.

The previous prime is 19981578217. The next prime is 19981578251. The reversal of 19981578240 is 4287518991.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (624).

It is a super-2 number, since 2×19981578240² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 74280826 + ... + 74281094.

It is an arithmetic number, because the mean of its divisors is an integer number (123847920).

Almost surely, 2^19981578240 is an apocalyptic number.

19981578240 is a gapful number since it is divisible by the number (10) 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 19981578240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38640551040).

19981578240 is an abundant number, since it is smaller than the sum of its proper divisors (57299523840).

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

19981578240 is a wasteful number, since it uses less digits than its factorization.

19981578240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 348 (or 323 counting only the distinct ones).

The product of its (nonzero) digits is 1451520, while the sum is 54.

The spelling of 19981578240 in words is "nineteen billion, nine hundred eighty-one million, five hundred seventy-eight thousand, two hundred forty".