1665666615 has 16 divisors (see below), whose sum is σ = 2730069216. Its totient is φ = 866688000.

The previous prime is 1665666589. The next prime is 1665666631. The reversal of 1665666615 is 5166665661.

It is not a de Polignac number, because 1665666615 - 2¹⁶ = 1665601079 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1353586 + ... + 1354815.

It is an arithmetic number, because the mean of its divisors is an integer number (170629326).

Almost surely, 2^1665666615 is an apocalyptic number.

1665666615 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1665666615 is a deficient number, since it is larger than the sum of its proper divisors (1064402601).

1665666615 is a wasteful number, since it uses less digits than its factorization.

1665666615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2708450.

The product of its digits is 1166400, while the sum is 48.

The square root of 1665666615 is about 40812.5791270290. The cubic root of 1665666615 is about 1185.3939155789.

The spelling of 1665666615 in words is "one billion, six hundred sixty-five million, six hundred sixty-six thousand, six hundred fifteen".