1666357081 has 8 divisors (see below), whose sum is σ = 1728171720. Its totient is φ = 1604832768.

The previous prime is 1666357039. The next prime is 1666357109. The reversal of 1666357081 is 1807536661.

It can be written as a sum of positive squares in 4 ways, for example, as 69155856 + 1597201225 = 8316^2 + 39965^2 .

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 1666357081 - 2⁷ = 1666356953 is a prime.

It is a super-2 number, since 2×1666357081² = 5553491842797681122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666357681) 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, 60856 + ... + 83881.

It is an arithmetic number, because the mean of its divisors is an integer number (216021465).

Almost surely, 2^1666357081 is an apocalyptic number.

It is an amenable number.

1666357081 is a deficient number, since it is larger than the sum of its proper divisors (61814639).

1666357081 is a wasteful number, since it uses less digits than its factorization.

1666357081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145163.

The product of its (nonzero) digits is 181440, while the sum is 43.

The square root of 1666357081 is about 40821.0372357195. The cubic root of 1666357081 is about 1185.5576860718.

The spelling of 1666357081 in words is "one billion, six hundred sixty-six million, three hundred fifty-seven thousand, eighty-one".