1666681000 has 48 divisors (see below), whose sum is σ = 3903056820. Its totient is φ = 666156000.

The previous prime is 1666680997. The next prime is 1666681001. The reversal of 1666681000 is 1866661.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 2 ways, for example, as 1126676356 + 540004644 = 33566^2 + 23238^2 .

It is a super-2 number, since 2×1666681000² = 5555651111522000000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1666681001) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1290355 + ... + 1291645.

Almost surely, 2^1666681000 is an apocalyptic number.

1666681000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1666681000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1951528410).

1666681000 is an abundant number, since it is smaller than the sum of its proper divisors (2236375820).

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

1666681000 is an frugal number, since it uses more digits than its factorization.

1666681000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2603 (or 1298 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 1666681000 is about 40825.0045927738. The cubic root of 1666681000 is about 1185.6345002961.

The spelling of 1666681000 in words is "one billion, six hundred sixty-six million, six hundred eighty-one thousand".