2121671561 has 8 divisors (see below), whose sum is σ = 2157544200. Its totient is φ = 2085834240.

The previous prime is 2121671543. The next prime is 2121671569. The reversal of 2121671561 is 1651761212.

It can be written as a sum of positive squares in 4 ways, for example, as 378108025 + 1743563536 = 19445^2 + 41756^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2121671561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2121671569) 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 7 ways as a sum of consecutive naturals, for example, 130745 + ... + 146073.

It is an arithmetic number, because the mean of its divisors is an integer number (269693025).

Almost surely, 2^2121671561 is an apocalyptic number.

It is an amenable number.

2121671561 is a deficient number, since it is larger than the sum of its proper divisors (35872639).

2121671561 is a wasteful number, since it uses less digits than its factorization.

2121671561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17659.

The product of its digits is 5040, while the sum is 32.

The square root of 2121671561 is about 46061.6061487222. The cubic root of 2121671561 is about 1284.9692011170.

The spelling of 2121671561 in words is "two billion, one hundred twenty-one million, six hundred seventy-one thousand, five hundred sixty-one".