1661711728 has 60 divisors (see below), whose sum is σ = 3543115240. Its totient is φ = 752830848.

The previous prime is 1661711717. The next prime is 1661711731. The reversal of 1661711728 is 8271171661.

It is a super-2 number, since 2×1661711728² = 5522571733945491968, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 155650 + ... + 165982.

Almost surely, 2^1661711728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1661711728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1771557620).

1661711728 is an abundant number, since it is smaller than the sum of its proper divisors (1881403512).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1661711728 is a wasteful number, since it uses less digits than its factorization.

1661711728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10406 (or 10377 counting only the distinct ones).

The product of its digits is 28224, while the sum is 40.

The square root of 1661711728 is about 40764.0985181814. The cubic root of 1661711728 is about 1184.4549893350.

The spelling of 1661711728 in words is "one billion, six hundred sixty-one million, seven hundred eleven thousand, seven hundred twenty-eight".