2991661 has 2 divisors, whose sum is σ = 2991662. Its totient is φ = 2991660.

The previous prime is 2991649. The next prime is 2991671. The reversal of 2991661 is 1661992.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2910436 + 81225 = 1706^2 + 285^2 .

It is a cyclic number.

It is not a de Polignac number, because 2991661 - 2⁵ = 2991629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2991601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1495830 + 1495831.

It is an arithmetic number, because the mean of its divisors is an integer number (1495831).

2^2991661 is an apocalyptic number.

It is an amenable number.

2991661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2991661 is an equidigital number, since it uses as much as digits as its factorization.

2991661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5832, while the sum is 34.

The square root of 2991661 is about 1729.6418704460. The cubic root of 2991661 is about 144.0912005861.

The spelling of 2991661 in words is "two million, nine hundred ninety-one thousand, six hundred sixty-one".