2161723897 has 4 divisors (see below), whose sum is σ = 2164351360. Its totient is φ = 2159096436.

The previous prime is 2161723873. The next prime is 2161723901. The reversal of 2161723897 is 7983271612.

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 not a de Polignac number, because 2161723897 - 2³¹ = 14240249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2161723807) 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, 1312497 + ... + 1314142.

It is an arithmetic number, because the mean of its divisors is an integer number (541087840).

Almost surely, 2^2161723897 is an apocalyptic number.

It is an amenable number.

2161723897 is a deficient number, since it is larger than the sum of its proper divisors (2627463).

2161723897 is an equidigital number, since it uses as much as digits as its factorization.

2161723897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2627462.

The product of its digits is 254016, while the sum is 46.

The square root of 2161723897 is about 46494.3426343464. The cubic root of 2161723897 is about 1293.0046136378.

The spelling of 2161723897 in words is "two billion, one hundred sixty-one million, seven hundred twenty-three thousand, eight hundred ninety-seven".