1661989800 has 48 divisors (see below), whose sum is σ = 5152170240. Its totient is φ = 443197120.

The previous prime is 1661989799. The next prime is 1661989811. The reversal of 1661989800 is 89891661.

It is a self number, because there is not a number n which added to its sum of digits gives 1661989800.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 1384392 + ... + 1385591.

It is an arithmetic number, because the mean of its divisors is an integer number (107336880).

Almost surely, 2^1661989800 is an apocalyptic number.

1661989800 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1661989800 is an abundant number, since it is smaller than the sum of its proper divisors (3490180440).

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

1661989800 is a wasteful number, since it uses less digits than its factorization.

1661989800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2770002 (or 2769993 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 48.

The square root of 1661989800 is about 40767.5091218485. The cubic root of 1661989800 is about 1184.5210548247.

The spelling of 1661989800 in words is "one billion, six hundred sixty-one million, nine hundred eighty-nine thousand, eight hundred".