1855681 has 8 divisors (see below), whose sum is σ = 1953000. Its totient is φ = 1760640.

The previous prime is 1855649. The next prime is 1855687. The reversal of 1855681 is 1865581.

It can be written as a sum of positive squares in 4 ways, for example, as 207025 + 1648656 = 455^2 + 1284^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1855681 - 2⁵ = 1855649 is a prime.

It is a super-2 number, since 2×1855681² = 6887103947522, which contains 22 as substring.

It is a Duffinian number.

1855681 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1855687) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1245 + ... + 2293.

It is an arithmetic number, because the mean of its divisors is an integer number (244125).

2^1855681 is an apocalyptic number.

It is an amenable number.

1855681 is a deficient number, since it is larger than the sum of its proper divisors (97319).

1855681 is a wasteful number, since it uses less digits than its factorization.

1855681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1139.

The product of its digits is 9600, while the sum is 34.

The square root of 1855681 is about 1362.2338272118. The cubic root of 1855681 is about 122.8856318980.

Subtracting from 1855681 its product of digits (9600), we obtain a triangular number (1846081 = T₁₉₂₁).

It can be divided in two parts, 1855 and 681, that multiplied together give a triangular number (1263255 = T₁₅₈₉).

The spelling of 1855681 in words is "one million, eight hundred fifty-five thousand, six hundred eighty-one".