3688781 has 2 divisors, whose sum is σ = 3688782. Its totient is φ = 3688780.

The previous prime is 3688777. The next prime is 3688787. The reversal of 3688781 is 1878863.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3118756 + 570025 = 1766^2 + 755^2 .

It is a cyclic number.

It is not a de Polignac number, because 3688781 - 2² = 3688777 is a prime.

It is a super-2 number, since 2×3688781² = 27214210531922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3688787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1844390 + 1844391.

It is an arithmetic number, because the mean of its divisors is an integer number (1844391).

Almost surely, 2^3688781 is an apocalyptic number.

It is an amenable number.

3688781 is a deficient number, since it is larger than the sum of its proper divisors (1).

3688781 is an equidigital number, since it uses as much as digits as its factorization.

3688781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64512, while the sum is 41.

The square root of 3688781 is about 1920.6199519947. The cubic root of 3688781 is about 154.5115529182.

The spelling of 3688781 in words is "three million, six hundred eighty-eight thousand, seven hundred eighty-one".