2857661 has 2 divisors, whose sum is σ = 2857662. Its totient is φ = 2857660.

The previous prime is 2857643. The next prime is 2857663. The reversal of 2857661 is 1667582.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2102500 + 755161 = 1450^2 + 869^2 .

It is a cyclic number.

It is not a de Polignac number, because 2857661 - 2¹⁸ = 2595517 is a prime.

It is a super-4 number, since 4×2857661⁴ (a number of 27 digits) contains 4444 as substring.

It is a Sophie Germain prime.

Together with 2857663, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2857663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1428830 + 1428831.

It is an arithmetic number, because the mean of its divisors is an integer number (1428831).

2^2857661 is an apocalyptic number.

It is an amenable number.

2857661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2857661 is an equidigital number, since it uses as much as digits as its factorization.

2857661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20160, while the sum is 35.

The square root of 2857661 is about 1690.4617712329. The cubic root of 2857661 is about 141.9069184333.

The spelling of 2857661 in words is "two million, eight hundred fifty-seven thousand, six hundred sixty-one".