1664374192021 has 2 divisors, whose sum is σ = 1664374192022. Its totient is φ = 1664374192020.

The previous prime is 1664374192001. The next prime is 1664374192031. The reversal of 1664374192021 is 1202914734661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1079323599025 + 585050592996 = 1038905^2 + 764886^2 .

It is a cyclic number.

It is not a de Polignac number, because 1664374192021 - 2²⁹ = 1663837321109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1664374192001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832187096010 + 832187096011.

It is an arithmetic number, because the mean of its divisors is an integer number (832187096011).

Almost surely, 2^{1664374192021} is an apocalyptic number.

It is an amenable number.

1664374192021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664374192021 is an equidigital number, since it uses as much as digits as its factorization.

1664374192021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 435456, while the sum is 46.

The spelling of 1664374192021 in words is "one trillion, six hundred sixty-four billion, three hundred seventy-four million, one hundred ninety-two thousand, twenty-one".