1981138800 has 60 divisors (see below), whose sum is σ = 6346251800. Its totient is φ = 528303360.

The previous prime is 1981138763. The next prime is 1981138801. The reversal of 1981138800 is 88311891.

It is a tau number, because it is divible by the number of its divisors (60).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981138801) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 824275 + ... + 826674.

Almost surely, 2^1981138800 is an apocalyptic number.

1981138800 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1981138800 is an abundant number, since it is smaller than the sum of its proper divisors (4365113000).

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

1981138800 is a wasteful number, since it uses less digits than its factorization.

1981138800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1650970 (or 1650959 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 39.

The square root of 1981138800 is about 44509.9853965377. The cubic root of 1981138800 is about 1255.9479301442.

The spelling of 1981138800 in words is "one billion, nine hundred eighty-one million, one hundred thirty-eight thousand, eight hundred".