3640725281 has 16 divisors (see below), whose sum is σ = 3844420608. Its totient is φ = 3443169600.

The previous prime is 3640725251. The next prime is 3640725293. The reversal of 3640725281 is 1825270463.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 3640725281 - 2³⁰ = 2566983457 is a prime.

It is a super-2 number, since 2×3640725281² = 26509761143425057922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (3640725211) 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, 290756 + ... + 303018.

It is an arithmetic number, because the mean of its divisors is an integer number (240276288).

Almost surely, 2^3640725281 is an apocalyptic number.

3640725281 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

3640725281 is a deficient number, since it is larger than the sum of its proper divisors (203695327).

3640725281 is a wasteful number, since it uses less digits than its factorization.

3640725281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12512.

The product of its (nonzero) digits is 80640, while the sum is 38.

The square root of 3640725281 is about 60338.4229243688. The cubic root of 3640725281 is about 1538.3764980146.

The spelling of 3640725281 in words is "three billion, six hundred forty million, seven hundred twenty-five thousand, two hundred eighty-one".