1665122215661 has 4 divisors (see below), whose sum is σ = 1689974786112. Its totient is φ = 1640269645212.

The previous prime is 1665122215649. The next prime is 1665122215681.

1665122215661 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1665122215661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665122215681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12426285125 + ... + 12426285258.

It is an arithmetic number, because the mean of its divisors is an integer number (422493696528).

Almost surely, 2^{1665122215661} is an apocalyptic number.

It is an amenable number.

1665122215661 is a deficient number, since it is larger than the sum of its proper divisors (24852570451).

1665122215661 is an equidigital number, since it uses as much as digits as its factorization.

1665122215661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24852570450.

The product of its digits is 259200, while the sum is 44.

The spelling of 1665122215661 in words is "one trillion, six hundred sixty-five billion, one hundred twenty-two million, two hundred fifteen thousand, six hundred sixty-one".