19987377661440 has 1600 divisors, whose sum is σ = 85701363422400. Its totient is φ = 4409945358336.

The previous prime is 19987377661423. The next prime is 19987377661463. The reversal of 19987377661440 is 4416677378991.

19987377661440 is a `hidden beast` number, since 1 + 9 + 9 + 87 + 37 + 76 + 6 + 1 + 440 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 4812754404 + ... + 4812758556.

It is an arithmetic number, because the mean of its divisors is an integer number (53563352139).

Almost surely, 2^{19987377661440} is an apocalyptic number.

19987377661440 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 19987377661440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42850681711200).

19987377661440 is an abundant number, since it is smaller than the sum of its proper divisors (65713985760960).

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

19987377661440 is an frugal number, since it uses more digits than its factorization.

19987377661440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4242 (or 4199 counting only the distinct ones).

The product of its (nonzero) digits is 384072192, while the sum is 72.

The spelling of 19987377661440 in words is "nineteen trillion, nine hundred eighty-seven billion, three hundred seventy-seven million, six hundred sixty-one thousand, four hundred forty".