1666680626 has 16 divisors (see below), whose sum is σ = 2693535768. Its totient is φ = 768892800.

The previous prime is 1666680619. The next prime is 1666680637. The reversal of 1666680626 is 6260866661.

It is a Cunningham number, because it is equal to 40825²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 246521401 + 1420159225 = 15701^2 + 37685^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 50336 + ... + 76596.

Almost surely, 2^1666680626 is an apocalyptic number.

1666680626 is a deficient number, since it is larger than the sum of its proper divisors (1026855142).

1666680626 is a wasteful number, since it uses less digits than its factorization.

1666680626 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28717.

The product of its (nonzero) digits is 746496, while the sum is 47.

The square root of 1666680626 is about 40825.0000122474. Note that the first 4 decimals coincide. The cubic root of 1666680626 is about 1185.6344116114.

The spelling of 1666680626 in words is "one billion, six hundred sixty-six million, six hundred eighty thousand, six hundred twenty-six".