1181989021 has 4 divisors (see below), whose sum is σ = 1233379872. Its totient is φ = 1130598172.

The previous prime is 1181989019. The next prime is 1181989033. The reversal of 1181989021 is 1209891811.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1181989021 - 2¹ = 1181989019 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1181989001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25695391 + ... + 25695436.

It is an arithmetic number, because the mean of its divisors is an integer number (308344968).

Almost surely, 2^1181989021 is an apocalyptic number.

It is an amenable number.

1181989021 is a deficient number, since it is larger than the sum of its proper divisors (51390851).

1181989021 is an equidigital number, since it uses as much as digits as its factorization.

1181989021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51390850.

The product of its (nonzero) digits is 10368, while the sum is 40.

The square root of 1181989021 is about 34380.0672047045. The cubic root of 1181989021 is about 1057.3152126045.

The spelling of 1181989021 in words is "one billion, one hundred eighty-one million, nine hundred eighty-nine thousand, twenty-one".