1665566026401 has 4 divisors (see below), whose sum is σ = 2220754701872. Its totient is φ = 1110377350932.

The previous prime is 1665566026373. The next prime is 1665566026427. The reversal of 1665566026401 is 1046206655661.

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 de Polignac number, because none of the positive numbers 2^k-1665566026401 is a prime.

It is a super-2 number, since 2×1665566026401² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1665566026001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 277594337731 + ... + 277594337736.

It is an arithmetic number, because the mean of its divisors is an integer number (555188675468).

Almost surely, 2^{1665566026401} is an apocalyptic number.

It is an amenable number.

1665566026401 is a deficient number, since it is larger than the sum of its proper divisors (555188675471).

1665566026401 is an equidigital number, since it uses as much as digits as its factorization.

1665566026401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 555188675470.

The product of its (nonzero) digits is 1555200, while the sum is 48.

The spelling of 1665566026401 in words is "one trillion, six hundred sixty-five billion, five hundred sixty-six million, twenty-six thousand, four hundred one".