1609090971821 has 2 divisors, whose sum is σ = 1609090971822. Its totient is φ = 1609090971820.

The previous prime is 1609090971809. The next prime is 1609090971857. The reversal of 1609090971821 is 1281790909061.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 850432551721 + 758658420100 = 922189^2 + 871010^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1609090971821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1609090971721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 804545485910 + 804545485911.

It is an arithmetic number, because the mean of its divisors is an integer number (804545485911).

Almost surely, 2^{1609090971821} is an apocalyptic number.

It is an amenable number.

1609090971821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1609090971821 is an equidigital number, since it uses as much as digits as its factorization.

1609090971821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 489888, while the sum is 53.

The spelling of 1609090971821 in words is "one trillion, six hundred nine billion, ninety million, nine hundred seventy-one thousand, eight hundred twenty-one".