1861668 has 18 divisors (see below), whose sum is σ = 4705974. Its totient is φ = 620544.

The previous prime is 1861663. The next prime is 1861697. The reversal of 1861668 is 8661681.

It can be written as a sum of positive squares in only one way, i.e., 1695204 + 166464 = 1302^2 + 408^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 51713 = 1861668 / (1 + 8 + 6 + 1 + 6 + 6 + 8).

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (1861661) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 25821 + ... + 25892.

It is an arithmetic number, because the mean of its divisors is an integer number (261443).

2^1861668 is an apocalyptic number.

1861668 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1861668 is an abundant number, since it is smaller than the sum of its proper divisors (2844306).

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

1861668 is a wasteful number, since it uses less digits than its factorization.

1861668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51723 (or 51718 counting only the distinct ones).

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

The square root of 1861668 is about 1364.4295511312. The cubic root of 1861668 is about 123.0176456937.

The spelling of 1861668 in words is "one million, eight hundred sixty-one thousand, six hundred sixty-eight".