2121178409 has 4 divisors (see below), whose sum is σ = 2424203904. Its totient is φ = 1818152916.

The previous prime is 2121178403. The next prime is 2121178459. The reversal of 2121178409 is 9048711212.

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 a de Polignac number, because none of the positive numbers 2^k-2121178409 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2121178403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 151512737 + ... + 151512750.

It is an arithmetic number, because the mean of its divisors is an integer number (606050976).

Almost surely, 2^2121178409 is an apocalyptic number.

It is an amenable number.

2121178409 is a deficient number, since it is larger than the sum of its proper divisors (303025495).

2121178409 is an equidigital number, since it uses as much as digits as its factorization.

2121178409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 303025494.

The product of its (nonzero) digits is 8064, while the sum is 35.

The square root of 2121178409 is about 46056.2526591124. The cubic root of 2121178409 is about 1284.8696358738.

The spelling of 2121178409 in words is "two billion, one hundred twenty-one million, one hundred seventy-eight thousand, four hundred nine".