2145323721 has 64 divisors (see below), whose sum is σ = 3223756800. Its totient is φ = 1262822400.

The previous prime is 2145323699. The next prime is 2145323723. The reversal of 2145323721 is 1273235412.

It is not a de Polignac number, because 2145323721 - 2⁶ = 2145323657 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2145323723) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 10167306 + ... + 10167516.

It is an arithmetic number, because the mean of its divisors is an integer number (50371200).

Almost surely, 2^2145323721 is an apocalyptic number.

It is an amenable number.

2145323721 is a deficient number, since it is larger than the sum of its proper divisors (1078433079).

2145323721 is a wasteful number, since it uses less digits than its factorization.

2145323721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 430.

The product of its digits is 10080, while the sum is 30.

The square root of 2145323721 is about 46317.6394152379. The cubic root of 2145323721 is about 1289.7264650485.

The spelling of 2145323721 in words is "two billion, one hundred forty-five million, three hundred twenty-three thousand, seven hundred twenty-one".