1666320281 has 8 divisors (see below), whose sum is σ = 1703842560. Its totient is φ = 1628884288.

The previous prime is 1666320259. The next prime is 1666320287. The reversal of 1666320281 is 1820236661.

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

It is a cyclic number.

It is not a de Polignac number, because 1666320281 - 2¹⁰ = 1666319257 is a prime.

It is a super-2 number, since 2×1666320281² = 5553246557743837922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666320287) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18305 + ... + 60561.

It is an arithmetic number, because the mean of its divisors is an integer number (212980320).

Almost surely, 2^1666320281 is an apocalyptic number.

It is an amenable number.

1666320281 is a deficient number, since it is larger than the sum of its proper divisors (37522279).

1666320281 is an equidigital number, since it uses as much as digits as its factorization.

1666320281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43143.

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 1666320281 is about 40820.5864852528. The cubic root of 1666320281 is about 1185.5489586819.

The spelling of 1666320281 in words is "one billion, six hundred sixty-six million, three hundred twenty thousand, two hundred eighty-one".