3681522721 has 4 divisors (see below), whose sum is σ = 3681868612. Its totient is φ = 3681176832.

The previous prime is 3681522683. The next prime is 3681522731. The reversal of 3681522721 is 1272251863.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1272251863 = 1367 ⋅930689.

It can be written as a sum of positive squares in 2 ways, for example, as 965966400 + 2715556321 = 31080^2 + 52111^2 .

It is a cyclic number.

It is not a de Polignac number, because 3681522721 - 2²⁷ = 3547304993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3681522731) 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, 156456 + ... + 178441.

It is an arithmetic number, because the mean of its divisors is an integer number (920467153).

Almost surely, 2^3681522721 is an apocalyptic number.

It is an amenable number.

3681522721 is a deficient number, since it is larger than the sum of its proper divisors (345891).

3681522721 is a wasteful number, since it uses less digits than its factorization.

3681522721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 345890.

The product of its digits is 40320, while the sum is 37.

The square root of 3681522721 is about 60675.5529105422. The cubic root of 3681522721 is about 1544.1014413885.

It can be divided in two parts, 36815 and 22721, that added together give a square (59536 = 244²).

The spelling of 3681522721 in words is "three billion, six hundred eighty-one million, five hundred twenty-two thousand, seven hundred twenty-one".