2491861 has 2 divisors, whose sum is σ = 2491862. Its totient is φ = 2491860.

The previous prime is 2491847. The next prime is 2491871. The reversal of 2491861 is 1681942.

It is a happy number.

2491861 is nontrivially palindromic in base 9.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2480625 + 11236 = 1575^2 + 106^2 .

It is a cyclic number.

It is not a de Polignac number, because 2491861 - 2⁵ = 2491829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2491871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1245930 + 1245931.

It is an arithmetic number, because the mean of its divisors is an integer number (1245931).

2^2491861 is an apocalyptic number.

It is an amenable number.

2491861 is a deficient number, since it is larger than the sum of its proper divisors (1).

2491861 is an equidigital number, since it uses as much as digits as its factorization.

2491861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3456, while the sum is 31.

The square root of 2491861 is about 1578.5629540820. The cubic root of 2491861 is about 135.5734364072.

The spelling of 2491861 in words is "two million, four hundred ninety-one thousand, eight hundred sixty-one".