1851220 has 36 divisors (see below), whose sum is σ = 4524660. Its totient is φ = 634368.

The previous prime is 1851217. The next prime is 1851253. The reversal of 1851220 is 221581.

It can be written as a sum of positive squares in 2 ways, for example, as 777924 + 1073296 = 882^2 + 1036^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 36 + ... + 1924.

It is an arithmetic number, because the mean of its divisors is an integer number (125685).

2^1851220 is an apocalyptic number.

1851220 is a gapful number since it is divisible by the number (10) 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 1851220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2262330).

1851220 is an abundant number, since it is smaller than the sum of its proper divisors (2673440).

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

1851220 is a wasteful number, since it uses less digits than its factorization.

1851220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1912 (or 1903 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 19.

The square root of 1851220 is about 1360.5954578786. The cubic root of 1851220 is about 122.7870817932.

The spelling of 1851220 in words is "one million, eight hundred fifty-one thousand, two hundred twenty".