5663981 has 4 divisors (see below), whose sum is σ = 5668764. Its totient is φ = 5659200.

The previous prime is 5663969. The next prime is 5663989. The reversal of 5663981 is 1893665.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1893665 = 5 ⋅378733.

It can be written as a sum of positive squares in 2 ways, for example, as 4141225 + 1522756 = 2035^2 + 1234^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-5663981 is a prime.

It is a super-2 number, since 2×5663981² = 64161361536722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (5663989) 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, 851 + ... + 3471.

It is an arithmetic number, because the mean of its divisors is an integer number (1417191).

Almost surely, 2^5663981 is an apocalyptic number.

It is an amenable number.

5663981 is a deficient number, since it is larger than the sum of its proper divisors (4783).

5663981 is a wasteful number, since it uses less digits than its factorization.

5663981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4782.

The product of its digits is 38880, while the sum is 38.

The square root of 5663981 is about 2379.9119731620. The cubic root of 5663981 is about 178.2545384185.

The spelling of 5663981 in words is "five million, six hundred sixty-three thousand, nine hundred eighty-one".