1981199121 has 8 divisors (see below), whose sum is σ = 2881744224. Its totient is φ = 1200726720.

The previous prime is 1981199117. The next prime is 1981199149. The reversal of 1981199121 is 1219911891.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1981199121 - 2² = 1981199117 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1981199021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30018136 + ... + 30018201.

It is an arithmetic number, because the mean of its divisors is an integer number (360218028).

Almost surely, 2^1981199121 is an apocalyptic number.

1981199121 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1981199121 is a deficient number, since it is larger than the sum of its proper divisors (900545103).

1981199121 is a wasteful number, since it uses less digits than its factorization.

1981199121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60036351.

The product of its digits is 11664, while the sum is 42.

The square root of 1981199121 is about 44510.6630033748. The cubic root of 1981199121 is about 1255.9606768981.

It can be divided in two parts, 1981 and 199121, that added together give a palindrome (201102).

The spelling of 1981199121 in words is "one billion, nine hundred eighty-one million, one hundred ninety-nine thousand, one hundred twenty-one".