1666225220665 has 16 divisors (see below), whose sum is σ = 2035943559360. Its totient is φ = 1308722068800.

The previous prime is 1666225220663. The next prime is 1666225220687. The reversal of 1666225220665 is 5660225226661.

It is not a de Polignac number, because 1666225220665 - 2¹ = 1666225220663 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1666225220663) 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, 3356286 + ... + 3820615.

It is an arithmetic number, because the mean of its divisors is an integer number (127246472460).

Almost surely, 2^{1666225220665} is an apocalyptic number.

It is an amenable number.

1666225220665 is a deficient number, since it is larger than the sum of its proper divisors (369718338695).

1666225220665 is an equidigital number, since it uses as much as digits as its factorization.

1666225220665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7177752.

The product of its (nonzero) digits is 3110400, while the sum is 49.

The spelling of 1666225220665 in words is "one trillion, six hundred sixty-six billion, two hundred twenty-five million, two hundred twenty thousand, six hundred sixty-five".