3663981 has 16 divisors (see below), whose sum is σ = 5488000. Its totient is φ = 2415744.

The previous prime is 3663971. The next prime is 3664013. The reversal of 3663981 is 1893663.

3663981 = 29² + 30² + ... + 222².

It is a happy number.

It is not a de Polignac number, because 3663981 - 2⁵ = 3663949 is a prime.

It is a super-2 number, since 2×3663981² = 26849513536722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3663911) 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, 1920 + ... + 3318.

It is an arithmetic number, because the mean of its divisors is an integer number (343000).

Almost surely, 2^3663981 is an apocalyptic number.

It is an amenable number.

3663981 is a deficient number, since it is larger than the sum of its proper divisors (1824019).

3663981 is a wasteful number, since it uses less digits than its factorization.

3663981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1505 (or 1499 counting only the distinct ones).

The product of its digits is 23328, while the sum is 36.

The square root of 3663981 is about 1914.1528152162. The cubic root of 3663981 is about 154.1645090843.

The spelling of 3663981 in words is "three million, six hundred sixty-three thousand, nine hundred eighty-one".