3121561 has 2 divisors, whose sum is σ = 3121562. Its totient is φ = 3121560.

The previous prime is 3121543. The next prime is 3121571. The reversal of 3121561 is 1651213.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3083536 + 38025 = 1756^2 + 195^2 .

It is an emirp because it is prime and its reverse (1651213) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3121561 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (3121571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1560780 + 1560781.

It is an arithmetic number, because the mean of its divisors is an integer number (1560781).

Almost surely, 2^3121561 is an apocalyptic number.

It is an amenable number.

3121561 is a deficient number, since it is larger than the sum of its proper divisors (1).

3121561 is an equidigital number, since it uses as much as digits as its factorization.

3121561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 180, while the sum is 19.

The square root of 3121561 is about 1766.7939891227. The cubic root of 3121561 is about 146.1472368415.

Adding to 3121561 its reverse (1651213), we get a palindrome (4772774).

The spelling of 3121561 in words is "three million, one hundred twenty-one thousand, five hundred sixty-one".