3636405721 has 16 divisors (see below), whose sum is σ = 3980805136. Its totient is φ = 3301502976.

The previous prime is 3636405709. The next prime is 3636405733. The reversal of 3636405721 is 1275046363.

It is an interprime number because it is at equal distance from previous prime (3636405709) and next prime (3636405733).

It can be written as a sum of positive squares in 8 ways, for example, as 288626121 + 3347779600 = 16989^2 + 57860^2 .

It is a cyclic number.

It is not a de Polignac number, because 3636405721 - 2¹⁹ = 3635881433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3636405701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 348841 + ... + 359113.

It is an arithmetic number, because the mean of its divisors is an integer number (248800321).

Almost surely, 2^3636405721 is an apocalyptic number.

It is an amenable number.

3636405721 is a deficient number, since it is larger than the sum of its proper divisors (344399415).

3636405721 is a wasteful number, since it uses less digits than its factorization.

3636405721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10732.

The product of its (nonzero) digits is 90720, while the sum is 37.

The square root of 3636405721 is about 60302.6178619138. The cubic root of 3636405721 is about 1537.7678519482.

The spelling of 3636405721 in words is "three billion, six hundred thirty-six million, four hundred five thousand, seven hundred twenty-one".