3643681 has 2 divisors, whose sum is σ = 3643682. Its totient is φ = 3643680.

The previous prime is 3643669. The next prime is 3643699. The reversal of 3643681 is 1863463.

3643681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2560000 + 1083681 = 1600^2 + 1041^2 .

It is a cyclic number.

It is not a de Polignac number, because 3643681 - 2¹¹ = 3641633 is a prime.

It is a super-2 number, since 2×3643681² = 26552822459522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3643621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1821840 + 1821841.

It is an arithmetic number, because the mean of its divisors is an integer number (1821841).

Almost surely, 2^3643681 is an apocalyptic number.

It is an amenable number.

3643681 is a deficient number, since it is larger than the sum of its proper divisors (1).

3643681 is an equidigital number, since it uses as much as digits as its factorization.

3643681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10368, while the sum is 31.

The square root of 3643681 is about 1908.8428431906. The cubic root of 3643681 is about 153.8792695187.

Subtracting from 3643681 its sum of digits (31), we obtain a triangular number (3643650 = T₂₆₉₉).

It can be divided in two parts, 36 and 43681, that multiplied together give a square (1572516 = 1254²).

The spelling of 3643681 in words is "three million, six hundred forty-three thousand, six hundred eighty-one".