1861640 has 32 divisors (see below), whose sum is σ = 4570560. Its totient is φ = 676800.

The previous prime is 1861637. The next prime is 1861649. The reversal of 1861640 is 461681.

It is not an unprimeable number, because it can be changed into a prime (1861649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1676 + ... + 2555.

It is an arithmetic number, because the mean of its divisors is an integer number (142830).

2^1861640 is an apocalyptic number.

1861640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1861640 is an abundant number, since it is smaller than the sum of its proper divisors (2708920).

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

1861640 is a wasteful number, since it uses less digits than its factorization.

1861640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4253 (or 4249 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 1861640 is about 1364.4192903943. The cubic root of 1861640 is about 123.0170289508.

The spelling of 1861640 in words is "one million, eight hundred sixty-one thousand, six hundred forty".