1666774265221 has 8 divisors (see below), whose sum is σ = 1900575180504. Its totient is φ = 1448057280000.

The previous prime is 1666774265209. The next prime is 1666774265231. The reversal of 1666774265221 is 1225624776661.

It can be written as a sum of positive squares in 4 ways, for example, as 47747057121 + 1619027208100 = 218511^2 + 1272410^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-1666774265221 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666774265231) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3770982280 + ... + 3770982721.

It is an arithmetic number, because the mean of its divisors is an integer number (237571897563).

Almost surely, 2^{1666774265221} is an apocalyptic number.

It is an amenable number.

1666774265221 is a deficient number, since it is larger than the sum of its proper divisors (233800915283).

1666774265221 is a wasteful number, since it uses less digits than its factorization.

1666774265221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7541965031.

The product of its digits is 10160640, while the sum is 55.

The spelling of 1666774265221 in words is "one trillion, six hundred sixty-six billion, seven hundred seventy-four million, two hundred sixty-five thousand, two hundred twenty-one".