1666391288 has 8 divisors (see below), whose sum is σ = 3124483680. Its totient is φ = 833195640.

The previous prime is 1666391273. The next prime is 1666391299. The reversal of 1666391288 is 8821936661.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104149448 + ... + 104149463.

It is an arithmetic number, because the mean of its divisors is an integer number (390560460).

Almost surely, 2^1666391288 is an apocalyptic number.

It is an amenable number.

1666391288 is a deficient number, since it is larger than the sum of its proper divisors (1458092392).

1666391288 is a wasteful number, since it uses less digits than its factorization.

1666391288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208298917 (or 208298913 counting only the distinct ones).

The product of its digits is 746496, while the sum is 50.

The square root of 1666391288 is about 40821.4562209630. The cubic root of 1666391288 is about 1185.5657983976.

The spelling of 1666391288 in words is "one billion, six hundred sixty-six million, three hundred ninety-one thousand, two hundred eighty-eight".