1661696961661 has 12 divisors (see below), whose sum is σ = 1840436069472. Its totient is φ = 1499102033000.

The previous prime is 1661696961653. The next prime is 1661696961709.

1661696961661 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1661696961661 - 2³ = 1661696961653 is a prime.

It is a super-2 number, since 2×1661696961661² (a number of 25 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1661696961593 and 1661696961602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661696961601) 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 in 11 ways as a sum of consecutive naturals, for example, 52400305 + ... + 52432006.

It is an arithmetic number, because the mean of its divisors is an integer number (153369672456).

Almost surely, 2^{1661696961661} is an apocalyptic number.

1661696961661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1661696961661 is a deficient number, since it is larger than the sum of its proper divisors (178739107811).

1661696961661 is a wasteful number, since it uses less digits than its factorization.

1661696961661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104832464 (or 104832453 counting only the distinct ones).

The product of its digits is 22674816, while the sum is 64.

The spelling of 1661696961661 in words is "one trillion, six hundred sixty-one billion, six hundred ninety-six million, nine hundred sixty-one thousand, six hundred sixty-one".