2181987993 has 8 divisors (see below), whose sum is σ = 2913322048. Its totient is φ = 1452656304.

The previous prime is 2181987959. The next prime is 2181988021. The reversal of 2181987993 is 3997891812.

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

It is not a de Polignac number, because 2181987993 - 2¹⁷ = 2181856921 is a prime.

It is a super-2 number, since 2×2181987993² = 9522143203192336098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2181987953) 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, 498046 + ... + 502407.

It is an arithmetic number, because the mean of its divisors is an integer number (364165256).

Almost surely, 2^2181987993 is an apocalyptic number.

It is an amenable number.

2181987993 is a deficient number, since it is larger than the sum of its proper divisors (731334055).

2181987993 is a wasteful number, since it uses less digits than its factorization.

2181987993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1001183.

The product of its digits is 1959552, while the sum is 57.

The square root of 2181987993 is about 46711.7543344285. The cubic root of 2181987993 is about 1297.0322821451.

The spelling of 2181987993 in words is "two billion, one hundred eighty-one million, nine hundred eighty-seven thousand, nine hundred ninety-three".