1666656901 has 16 divisors (see below), whose sum is σ = 2058550144. Its totient is φ = 1313993664.

The previous prime is 1666656899. The next prime is 1666656947. The reversal of 1666656901 is 1096566661.

It is a cyclic number.

It is not a de Polignac number, because 1666656901 - 2¹ = 1666656899 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666656961) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6606 + ... + 58111.

It is an arithmetic number, because the mean of its divisors is an integer number (128659384).

Almost surely, 2^1666656901 is an apocalyptic number.

It is an amenable number.

1666656901 is a deficient number, since it is larger than the sum of its proper divisors (391893243).

1666656901 is a wasteful number, since it uses less digits than its factorization.

1666656901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65020.

The product of its (nonzero) digits is 349920, while the sum is 46.

The square root of 1666656901 is about 40824.7094417094. The cubic root of 1666656901 is about 1185.6287857965.

The spelling of 1666656901 in words is "one billion, six hundred sixty-six million, six hundred fifty-six thousand, nine hundred one".