2972181721 has 4 divisors (see below), whose sum is σ = 2973590452. Its totient is φ = 2970772992.

The previous prime is 2972181697. The next prime is 2972181727. The reversal of 2972181721 is 1271812792.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1358954496 + 1613227225 = 36864^2 + 40165^2 .

It is a cyclic number.

It is not a de Polignac number, because 2972181721 - 2¹¹ = 2972179673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2972181727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 701196 + ... + 705421.

It is an arithmetic number, because the mean of its divisors is an integer number (743397613).

Almost surely, 2^2972181721 is an apocalyptic number.

It is an amenable number.

2972181721 is a deficient number, since it is larger than the sum of its proper divisors (1408731).

2972181721 is a wasteful number, since it uses less digits than its factorization.

2972181721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1408730.

The product of its digits is 28224, while the sum is 40.

The square root of 2972181721 is about 54517.7193305076. The cubic root of 2972181721 is about 1437.7778420579. Note that the first 3 decimals are identical.

The spelling of 2972181721 in words is "two billion, nine hundred seventy-two million, one hundred eighty-one thousand, seven hundred twenty-one".