3655681 has 2 divisors, whose sum is σ = 3655682. Its totient is φ = 3655680.

The previous prime is 3655667. The next prime is 3655693. The reversal of 3655681 is 1865563.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2480625 + 1175056 = 1575^2 + 1084^2 .

It is a cyclic number.

It is not a de Polignac number, because 3655681 - 2⁵ = 3655649 is a prime.

It is a super-2 number, since 2×3655681² = 26728007147522, which contains 22 as substring.

3655681 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (3655651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1827840 + 1827841.

It is an arithmetic number, because the mean of its divisors is an integer number (1827841).

It is a Proth number, since it is equal to 1785 ⋅ 2¹¹ + 1 and 1785 < 2¹¹.

Almost surely, 2^3655681 is an apocalyptic number.

It is an amenable number.

3655681 is a deficient number, since it is larger than the sum of its proper divisors (1).

3655681 is an equidigital number, since it uses as much as digits as its factorization.

3655681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21600, while the sum is 34.

The square root of 3655681 is about 1911.9835250336. The cubic root of 3655681 is about 154.0480116788.

The spelling of 3655681 in words is "three million, six hundred fifty-five thousand, six hundred eighty-one".