1666720620215 has 48 divisors (see below), whose sum is σ = 2409809784480. Its totient is φ = 1102119540480.

The previous prime is 1666720620211. The next prime is 1666720620241. The reversal of 1666720620215 is 5120260276661.

It is not a de Polignac number, because 1666720620215 - 2² = 1666720620211 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666720620211) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5617529 + ... + 5906781.

It is an arithmetic number, because the mean of its divisors is an integer number (50204370510).

Almost surely, 2^{1666720620215} is an apocalyptic number.

1666720620215 is a deficient number, since it is larger than the sum of its proper divisors (743089164265).

1666720620215 is a wasteful number, since it uses less digits than its factorization.

1666720620215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290112 (or 290105 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 44.

Adding to 1666720620215 its reverse (5120260276661), we get a palindrome (6786980896876).

The spelling of 1666720620215 in words is "one trillion, six hundred sixty-six billion, seven hundred twenty million, six hundred twenty thousand, two hundred fifteen".