3640999581 has 6 divisors (see below), whose sum is σ = 5259221630. Its totient is φ = 2427333048.

The previous prime is 3640999577. The next prime is 3640999597. The reversal of 3640999581 is 1859990463.

It can be written as a sum of positive squares in only one way, i.e., 2710139481 + 930860100 = 52059^2 + 30510^2 .

It is not a de Polignac number, because 3640999581 - 2² = 3640999577 is a prime.

It is a super-2 number, since 2×3640999581² = 26513755897684351122, 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 (3640995581) 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 5 ways as a sum of consecutive naturals, for example, 202277746 + ... + 202277763.

Almost surely, 2^3640999581 is an apocalyptic number.

It is an amenable number.

3640999581 is a deficient number, since it is larger than the sum of its proper divisors (1618222049).

3640999581 is a wasteful number, since it uses less digits than its factorization.

3640999581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 404555515 (or 404555512 counting only the distinct ones).

The product of its (nonzero) digits is 2099520, while the sum is 54.

The square root of 3640999581 is about 60340.6958942305. The cubic root of 3640999581 is about 1538.4151318987.

It can be divided in two parts, 364099 and 9581, that added together give a triangular number (373680 = T₈₆₄).

The spelling of 3640999581 in words is "three billion, six hundred forty million, nine hundred ninety-nine thousand, five hundred eighty-one".