2161221049 has 4 divisors (see below), whose sum is σ = 2327468836. Its totient is φ = 1994973264.

The previous prime is 2161220977. The next prime is 2161221061. The reversal of 2161221049 is 9401221612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 367105600 + 1794115449 = 19160^2 + 42357^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2161221049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2161221449) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 83123874 + ... + 83123899.

It is an arithmetic number, because the mean of its divisors is an integer number (581867209).

Almost surely, 2^2161221049 is an apocalyptic number.

It is an amenable number.

2161221049 is a deficient number, since it is larger than the sum of its proper divisors (166247787).

2161221049 is a wasteful number, since it uses less digits than its factorization.

2161221049 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166247786.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 2161221049 is about 46488.9346941829. The cubic root of 2161221049 is about 1292.9043487203.

The spelling of 2161221049 in words is "two billion, one hundred sixty-one million, two hundred twenty-one thousand, forty-nine".