1861311 has 4 divisors (see below), whose sum is σ = 2481752. Its totient is φ = 1240872.

The previous prime is 1861309. The next prime is 1861331. The reversal of 1861311 is 1131681.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1861311 - 2¹ = 1861309 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1861331) 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, 310216 + ... + 310221.

It is an arithmetic number, because the mean of its divisors is an integer number (620438).

2^1861311 is an apocalyptic number.

1861311 is a deficient number, since it is larger than the sum of its proper divisors (620441).

1861311 is an equidigital number, since it uses as much as digits as its factorization.

1861311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 620440.

The product of its digits is 144, while the sum is 21.

The square root of 1861311 is about 1364.2987209552. The cubic root of 1861311 is about 123.0097817589.

Adding to 1861311 its reverse (1131681), we get a palindrome (2992992).

The spelling of 1861311 in words is "one million, eight hundred sixty-one thousand, three hundred eleven".