19997655408 has 160 divisors (see below), whose sum is σ = 58506969600. Its totient is φ = 6537945600.

The previous prime is 19997655389. The next prime is 19997655451. The reversal of 19997655408 is 80455679991.

19997655408 is a `hidden beast` number, since 1 + 9 + 9 + 9 + 76 + 554 + 0 + 8 = 666.

It is a super-2 number, since 2×19997655408² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19395853 + ... + 19396883.

It is an arithmetic number, because the mean of its divisors is an integer number (365668560).

Almost surely, 2^19997655408 is an apocalyptic number.

19997655408 is a gapful number since it is divisible by the number (18) 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 19997655408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29253484800).

19997655408 is an abundant number, since it is smaller than the sum of its proper divisors (38509314192).

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

19997655408 is a wasteful number, since it uses less digits than its factorization.

19997655408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1868 (or 1856 counting only the distinct ones).

The product of its (nonzero) digits is 24494400, while the sum is 63.

The spelling of 19997655408 in words is "nineteen billion, nine hundred ninety-seven million, six hundred fifty-five thousand, four hundred eight".