1664128214661 has 24 divisors (see below), whose sum is σ = 2439106024320. Its totient is φ = 1008472241920.

The previous prime is 1664128214647. The next prime is 1664128214717.

1664128214661 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1664128214661 - 2⁶ = 1664128214597 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1664128214661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664128214261) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3970996 + ... + 4370018.

It is an arithmetic number, because the mean of its divisors is an integer number (101629417680).

Almost surely, 2^{1664128214661} is an apocalyptic number.

1664128214661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1664128214661 is a deficient number, since it is larger than the sum of its proper divisors (774977809659).

1664128214661 is a wasteful number, since it uses less digits than its factorization.

1664128214661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 410537 (or 410526 counting only the distinct ones).

The product of its digits is 663552, while the sum is 48.

The spelling of 1664128214661 in words is "one trillion, six hundred sixty-four billion, one hundred twenty-eight million, two hundred fourteen thousand, six hundred sixty-one".