3639261721 has 16 divisors (see below), whose sum is σ = 3780604800. Its totient is φ = 3500784000.

The previous prime is 3639261701. The next prime is 3639261737. The reversal of 3639261721 is 1271629363.

It is a happy number.

It is not a de Polignac number, because 3639261721 - 2¹⁵ = 3639228953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3639261701) 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 15 ways as a sum of consecutive naturals, for example, 858435 + ... + 862663.

It is an arithmetic number, because the mean of its divisors is an integer number (236287800).

Almost surely, 2^3639261721 is an apocalyptic number.

It is an amenable number.

3639261721 is a deficient number, since it is larger than the sum of its proper divisors (141343079).

3639261721 is a wasteful number, since it uses less digits than its factorization.

3639261721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4560.

The product of its digits is 81648, while the sum is 40.

The square root of 3639261721 is about 60326.2937780865. The cubic root of 3639261721 is about 1538.1703295636.

The spelling of 3639261721 in words is "three billion, six hundred thirty-nine million, two hundred sixty-one thousand, seven hundred twenty-one".