1001001666 has 16 divisors (see below), whose sum is σ = 2288003904. Its totient is φ = 286000464.

The previous prime is 1001001647. The next prime is 1001001691. The reversal of 1001001666 is 6661001001.

It is a Harshad number since it is a multiple of its sum of digits (21).

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, 11916645 + ... + 11916728.

It is an arithmetic number, because the mean of its divisors is an integer number (143000244).

Almost surely, 2^1001001666 is an apocalyptic number.

1001001666 is an abundant number, since it is smaller than the sum of its proper divisors (1287002238).

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

1001001666 is a wasteful number, since it uses less digits than its factorization.

1001001666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23833385.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 1001001666 is about 31638.6103677137. The cubic root of 1001001666 is about 1000.3337772470. Note that the first 3 decimals are identical.

Adding to 1001001666 its reverse (6661001001), we get a palindrome (7662002667).

It can be divided in two parts, 1001001 and 666, that multiplied together give a palindrome (666666666).

The spelling of 1001001666 in words is "one billion, one million, one thousand, six hundred sixty-six".