1661955689 has 8 divisors (see below), whose sum is σ = 1734676800. Its totient is φ = 1589273136.

The previous prime is 1661955671. The next prime is 1661955721. The reversal of 1661955689 is 9865591661.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1661955689 - 2²⁴ = 1645178473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1661955389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 110387 + ... + 124535.

It is an arithmetic number, because the mean of its divisors is an integer number (216834600).

Almost surely, 2^1661955689 is an apocalyptic number.

It is an amenable number.

1661955689 is a deficient number, since it is larger than the sum of its proper divisors (72721111).

1661955689 is a wasteful number, since it uses less digits than its factorization.

1661955689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19279.

The product of its digits is 3499200, while the sum is 56.

The square root of 1661955689 is about 40767.0907595820. The cubic root of 1661955689 is about 1184.5129509896.

The spelling of 1661955689 in words is "one billion, six hundred sixty-one million, nine hundred fifty-five thousand, six hundred eighty-nine".