1555861 has 2 divisors, whose sum is σ = 1555862. Its totient is φ = 1555860.

The previous prime is 1555847. The next prime is 1555901. The reversal of 1555861 is 1685551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1232100 + 323761 = 1110^2 + 569^2 .

It is a cyclic number.

It is not a de Polignac number, because 1555861 - 2⁷ = 1555733 is a prime.

It is a Chen prime.

1555861 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1555831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 777930 + 777931.

It is an arithmetic number, because the mean of its divisors is an integer number (777931).

2^1555861 is an apocalyptic number.

It is an amenable number.

1555861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1555861 is an equidigital number, since it uses as much as digits as its factorization.

1555861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6000, while the sum is 31.

The square root of 1555861 is about 1247.3415731066. The cubic root of 1555861 is about 115.8751381406.

The spelling of 1555861 in words is "one million, five hundred fifty-five thousand, eight hundred sixty-one".