1866663681 has 8 divisors (see below), whose sum is σ = 2491713504. Its totient is φ = 1243028160.

The previous prime is 1866663649. The next prime is 1866663737. The reversal of 1866663681 is 1863666681.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1866663681 - 2⁵ = 1866663649 is a prime.

It is a super-2 number, since 2×1866663681² = 6968866595928939522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1866663781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 350491 + ... + 355776.

It is an arithmetic number, because the mean of its divisors is an integer number (311464188).

Almost surely, 2^1866663681 is an apocalyptic number.

It is an amenable number.

1866663681 is a deficient number, since it is larger than the sum of its proper divisors (625049823).

1866663681 is an equidigital number, since it uses as much as digits as its factorization.

1866663681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 707151.

The product of its digits is 1492992, while the sum is 51.

The square root of 1866663681 is about 43204.9034369943. The cubic root of 1866663681 is about 1231.2758438373.

The spelling of 1866663681 in words is "one billion, eight hundred sixty-six million, six hundred sixty-three thousand, six hundred eighty-one".