1666680625 has 45 divisors (see below), whose sum is σ = 2208268909. Its totient is φ = 1257410000.

The previous prime is 1666680619. The next prime is 1666680637. The reversal of 1666680625 is 5260866661.

The square root of 1666680625 is 40825.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 2 ways, for example, as 130667761 + 1536012864 = 11431^2 + 39192^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1666680625 is a prime.

It is a Smith number, since the sum of its digits (46) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 23474340 + ... + 23474410.

Almost surely, 2^1666680625 is an apocalyptic number.

1666680625 is the 40825-th square number.

1666680625 is the 20413-rd centered octagonal number.

It is an amenable number.

1666680625 is a deficient number, since it is larger than the sum of its proper divisors (541588284).

1666680625 is an frugal number, since it uses more digits than its factorization.

1666680625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208 (or 99 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 46.

The cubic root of 1666680625 is about 1185.6344113743.

The spelling of 1666680625 in words is "one billion, six hundred sixty-six million, six hundred eighty thousand, six hundred twenty-five".