1871861 has 4 divisors (see below), whose sum is σ = 1970400. Its totient is φ = 1773324.

The previous prime is 1871851. The next prime is 1871879. The reversal of 1871861 is 1681781.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1681781 = 31 ⋅54251.

It is a cyclic number.

It is not a de Polignac number, because 1871861 - 2¹⁸ = 1609717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1871851) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 49241 + ... + 49278.

It is an arithmetic number, because the mean of its divisors is an integer number (492600).

2^1871861 is an apocalyptic number.

It is an amenable number.

1871861 is a deficient number, since it is larger than the sum of its proper divisors (98539).

1871861 is an equidigital number, since it uses as much as digits as its factorization.

1871861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98538.

The product of its digits is 2688, while the sum is 32.

The square root of 1871861 is about 1368.1597128990. The cubic root of 1871861 is about 123.2417524828.

It can be divided in two parts, 187 and 1861, that added together give a 11-th power (2048 = 2¹¹).

The spelling of 1871861 in words is "one million, eight hundred seventy-one thousand, eight hundred sixty-one".