1291861 has 2 divisors, whose sum is σ = 1291862. Its totient is φ = 1291860.

The previous prime is 1291831. The next prime is 1291877. The reversal of 1291861 is 1681921.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 828100 + 463761 = 910^2 + 681^2 .

It is a cyclic number.

It is not a de Polignac number, because 1291861 - 2⁹ = 1291349 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1291831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645930 + 645931.

It is an arithmetic number, because the mean of its divisors is an integer number (645931).

2^1291861 is an apocalyptic number.

It is an amenable number.

1291861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291861 is an equidigital number, since it uses as much as digits as its factorization.

1291861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 864, while the sum is 28.

The square root of 1291861 is about 1136.6006334681. The cubic root of 1291861 is about 108.9110460179.

The spelling of 1291861 in words is "one million, two hundred ninety-one thousand, eight hundred sixty-one".