3123781 has 2 divisors, whose sum is σ = 3123782. Its totient is φ = 3123780.

The previous prime is 3123779. The next prime is 3123797. The reversal of 3123781 is 1873213.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1846881 + 1276900 = 1359^2 + 1130^2 .

It is a cyclic number.

It is not a de Polignac number, because 3123781 - 2¹ = 3123779 is a prime.

It is a super-2 number, since 2×3123781² = 19516015471922, which contains 22 as substring.

Together with 3123779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3123721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1561890 + 1561891.

It is an arithmetic number, because the mean of its divisors is an integer number (1561891).

Almost surely, 2^3123781 is an apocalyptic number.

It is an amenable number.

3123781 is a deficient number, since it is larger than the sum of its proper divisors (1).

3123781 is an equidigital number, since it uses as much as digits as its factorization.

3123781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008, while the sum is 25.

The square root of 3123781 is about 1767.4221340698. The cubic root of 3123781 is about 146.1818744243.

Adding to 3123781 its reverse (1873213), we get a palindrome (4996994).

The spelling of 3123781 in words is "three million, one hundred twenty-three thousand, seven hundred eighty-one".