1669605909661 has 4 divisors (see below), whose sum is σ = 1767818022012. Its totient is φ = 1571393797312.

The previous prime is 1669605909611. The next prime is 1669605909667. The reversal of 1669605909661 is 1669095069661.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1036914524100 + 632691385561 = 1018290^2 + 795419^2 .

It is a cyclic number.

It is not a de Polignac number, because 1669605909661 - 2⁷ = 1669605909533 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1669605909593 and 1669605909602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1669605909667) 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, 49106056150 + ... + 49106056183.

It is an arithmetic number, because the mean of its divisors is an integer number (441954505503).

Almost surely, 2^{1669605909661} is an apocalyptic number.

It is an amenable number.

1669605909661 is a deficient number, since it is larger than the sum of its proper divisors (98212112351).

1669605909661 is an equidigital number, since it uses as much as digits as its factorization.

1669605909661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98212112350.

The product of its (nonzero) digits is 28343520, while the sum is 64.

The spelling of 1669605909661 in words is "one trillion, six hundred sixty-nine billion, six hundred five million, nine hundred nine thousand, six hundred sixty-one".