1861663 has 2 divisors, whose sum is σ = 1861664. Its totient is φ = 1861662.

The previous prime is 1861661. The next prime is 1861697. The reversal of 1861663 is 3661681.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1861663 - 2¹ = 1861661 is a prime.

Together with 1861661, it forms a pair of twin primes.

1861663 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1861661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 930831 + 930832.

It is an arithmetic number, because the mean of its divisors is an integer number (930832).

2^1861663 is an apocalyptic number.

1861663 is a deficient number, since it is larger than the sum of its proper divisors (1).

1861663 is an equidigital number, since it uses as much as digits as its factorization.

1861663 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 31.

The square root of 1861663 is about 1364.4277188624. The cubic root of 1861663 is about 123.0175355615.

It can be divided in two parts, 186 and 1663, that added together give a square (1849 = 43²).

The spelling of 1861663 in words is "one million, eight hundred sixty-one thousand, six hundred sixty-three".