2161020261 has 16 divisors (see below), whose sum is σ = 3054699008. Its totient is φ = 1356523200.

The previous prime is 2161020217. The next prime is 2161020293. The reversal of 2161020261 is 1620201612.

It is not a de Polignac number, because 2161020261 - 2¹¹ = 2161018213 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 (2161040261) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 310570 + ... + 317451.

It is an arithmetic number, because the mean of its divisors is an integer number (190918688).

Almost surely, 2^2161020261 is an apocalyptic number.

It is an amenable number.

2161020261 is a deficient number, since it is larger than the sum of its proper divisors (893678747).

2161020261 is a wasteful number, since it uses less digits than its factorization.

2161020261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 628092.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 2161020261 is about 46486.7751193821. The cubic root of 2161020261 is about 1292.8643084357.

Adding to 2161020261 its reverse (1620201612), we get a palindrome (3781221873).

The spelling of 2161020261 in words is "two billion, one hundred sixty-one million, twenty thousand, two hundred sixty-one".