3638661581 has 16 divisors (see below), whose sum is σ = 3807051840. Its totient is φ = 3473272320.

The previous prime is 3638661541. The next prime is 3638661583. The reversal of 3638661581 is 1851668363.

3638661581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3638661581 is a prime.

It is a super-2 number, since 2×3638661581² = 26479716202090839122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3638661583) 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, 2143325 + ... + 2145021.

It is an arithmetic number, because the mean of its divisors is an integer number (237940740).

Almost surely, 2^3638661581 is an apocalyptic number.

It is an amenable number.

3638661581 is a deficient number, since it is larger than the sum of its proper divisors (168390259).

3638661581 is a wasteful number, since it uses less digits than its factorization.

3638661581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2524.

The product of its digits is 622080, while the sum is 47.

The square root of 3638661581 is about 60321.3194567228. The cubic root of 3638661581 is about 1538.0857731930.

The spelling of 3638661581 in words is "three billion, six hundred thirty-eight million, six hundred sixty-one thousand, five hundred eighty-one".