1809864 has 144 divisors (see below), whose sum is σ = 6224400. Its totient is φ = 489888.

The previous prime is 1809859. The next prime is 1809881. The reversal of 1809864 is 4689081.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 95247 + ... + 95265.

It is an arithmetic number, because the mean of its divisors is an integer number (43225).

2^1809864 is an apocalyptic number.

1809864 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1809864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3112200).

1809864 is an abundant number, since it is smaller than the sum of its proper divisors (4414536).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1809864 is a wasteful number, since it uses less digits than its factorization.

1809864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54 (or 31 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 1809864 is about 1345.3118597559. The cubic root of 1809864 is about 121.8658383646.

The spelling of 1809864 in words is "one million, eight hundred nine thousand, eight hundred sixty-four".