19771971800 has 96 divisors (see below), whose sum is σ = 52737696000. Its totient is φ = 6753060480.

The previous prime is 19771971787. The next prime is 19771971803. The reversal of 19771971800 is 817917791.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (50).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19771971803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 341351 + ... + 395049.

It is an arithmetic number, because the mean of its divisors is an integer number (549351000).

Almost surely, 2^19771971800 is an apocalyptic number.

19771971800 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 19771971800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26368848000).

19771971800 is an abundant number, since it is smaller than the sum of its proper divisors (32965724200).

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

19771971800 is a wasteful number, since it uses less digits than its factorization.

19771971800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53985 (or 53976 counting only the distinct ones).

The product of its (nonzero) digits is 222264, while the sum is 50.

The spelling of 19771971800 in words is "nineteen billion, seven hundred seventy-one million, nine hundred seventy-one thousand, eight hundred".