1855591 has 2 divisors, whose sum is σ = 1855592. Its totient is φ = 1855590.

The previous prime is 1855589. The next prime is 1855603. The reversal of 1855591 is 1955581.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1855591 - 2¹ = 1855589 is a prime.

Together with 1855589, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1855501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 927795 + 927796.

It is an arithmetic number, because the mean of its divisors is an integer number (927796).

2^1855591 is an apocalyptic number.

1855591 is a deficient number, since it is larger than the sum of its proper divisors (1).

1855591 is an equidigital number, since it uses as much as digits as its factorization.

1855591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9000, while the sum is 34.

The square root of 1855591 is about 1362.2007928349. The cubic root of 1855591 is about 122.8836452265.

It can be divided in two parts, 185 and 5591, that added together give a square (5776 = 76²).

The spelling of 1855591 in words is "one million, eight hundred fifty-five thousand, five hundred ninety-one".