1861391 has 8 divisors (see below), whose sum is σ = 2163840. Its totient is φ = 1568088.

The previous prime is 1861351. The next prime is 1861397. The reversal of 1861391 is 1931681.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1861391 is a prime.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1861397) 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, 1841 + ... + 2666.

It is an arithmetic number, because the mean of its divisors is an integer number (270480).

2^1861391 is an apocalyptic number.

1861391 is a deficient number, since it is larger than the sum of its proper divisors (302449).

1861391 is an equidigital number, since it uses as much as digits as its factorization.

1861391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4573.

The product of its digits is 1296, while the sum is 29.

The square root of 1861391 is about 1364.3280397324. The cubic root of 1861391 is about 123.0115440726.

The spelling of 1861391 in words is "one million, eight hundred sixty-one thousand, three hundred ninety-one".