2161821273 has 16 divisors (see below), whose sum is σ = 3083880000. Its totient is φ = 1342975680.

The previous prime is 2161821257. The next prime is 2161821287. The reversal of 2161821273 is 3721281612.

It is not a de Polignac number, because 2161821273 - 2⁴ = 2161821257 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2161821223) 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, 307398 + ... + 314351.

It is an arithmetic number, because the mean of its divisors is an integer number (192742500).

Almost surely, 2^2161821273 is an apocalyptic number.

It is an amenable number.

2161821273 is a deficient number, since it is larger than the sum of its proper divisors (922058727).

2161821273 is a wasteful number, since it uses less digits than its factorization.

2161821273 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 621832.

The product of its digits is 8064, while the sum is 33.

The square root of 2161821273 is about 46495.3898037214. The cubic root of 2161821273 is about 1293.0240280393.

The spelling of 2161821273 in words is "two billion, one hundred sixty-one million, eight hundred twenty-one thousand, two hundred seventy-three".