3685721609 has 4 divisors (see below), whose sum is σ = 3775617300. Its totient is φ = 3595825920.

The previous prime is 3685721597. The next prime is 3685721701. The reversal of 3685721609 is 9061275863.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9061275863 = 30211 ⋅299933.

It can be written as a sum of positive squares in 2 ways, for example, as 1848742009 + 1836979600 = 42997^2 + 42860^2 .

It is a cyclic number.

It is not a de Polignac number, because 3685721609 - 2⁸ = 3685721353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3685721009) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44947784 + ... + 44947865.

It is an arithmetic number, because the mean of its divisors is an integer number (943904325).

Almost surely, 2^3685721609 is an apocalyptic number.

It is an amenable number.

3685721609 is a deficient number, since it is larger than the sum of its proper divisors (89895691).

3685721609 is an equidigital number, since it uses as much as digits as its factorization.

3685721609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89895690.

The product of its (nonzero) digits is 544320, while the sum is 47.

The square root of 3685721609 is about 60710.1442017724. The cubic root of 3685721609 is about 1544.6882498177.

The spelling of 3685721609 in words is "three billion, six hundred eighty-five million, seven hundred twenty-one thousand, six hundred nine".