2161221047 has 4 divisors (see below), whose sum is σ = 2161899000. Its totient is φ = 2160543096.

The previous prime is 2161220977. The next prime is 2161221061. The reversal of 2161221047 is 7401221612.

2161221047 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 2161221047 - 2¹⁰ = 2161220023 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161221247) 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, 334172 + ... + 340577.

It is an arithmetic number, because the mean of its divisors is an integer number (540474750).

Almost surely, 2^2161221047 is an apocalyptic number.

2161221047 is a deficient number, since it is larger than the sum of its proper divisors (677953).

2161221047 is an equidigital number, since it uses as much as digits as its factorization.

2161221047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 677952.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 2161221047 is about 46488.9346726724. The cubic root of 2161221047 is about 1292.9043483215.

Adding to 2161221047 its reverse (7401221612), we get a palindrome (9562442659).

The spelling of 2161221047 in words is "two billion, one hundred sixty-one million, two hundred twenty-one thousand, forty-seven".