1851645640 has 64 divisors (see below), whose sum is σ = 4492681200. Its totient is φ = 682770432.

The previous prime is 1851645619. The next prime is 1851645643. The reversal of 1851645640 is 465461581.

It can be written as a sum of positive squares in 8 ways, for example, as 3849444 + 1847796196 = 1962^2 + 42986^2 .

It is a super-2 number, since 2×1851645640² = 6857183152262019200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 1851645593 and 1851645602.

It is not an unprimeable number, because it can be changed into a prime (1851645643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 481164 + ... + 484996.

Almost surely, 2^1851645640 is an apocalyptic number.

1851645640 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 1851645640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2246340600).

1851645640 is an abundant number, since it is smaller than the sum of its proper divisors (2641035560).

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

1851645640 is a wasteful number, since it uses less digits than its factorization.

1851645640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4786 (or 4782 counting only the distinct ones).

The product of its (nonzero) digits is 115200, while the sum is 40.

The square root of 1851645640 is about 43030.7522592855. The cubic root of 1851645640 is about 1227.9649163973.

The spelling of 1851645640 in words is "one billion, eight hundred fifty-one million, six hundred forty-five thousand, six hundred forty".