1661988660 has 24 divisors (see below), whose sum is σ = 4653568416. Its totient is φ = 443196960.

The previous prime is 1661988659. The next prime is 1661988677. The reversal of 1661988660 is 668891661.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13849846 + ... + 13849965.

It is an arithmetic number, because the mean of its divisors is an integer number (193898684).

Almost surely, 2^1661988660 is an apocalyptic number.

1661988660 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1661988660 is an abundant number, since it is smaller than the sum of its proper divisors (2991579756).

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

1661988660 is a wasteful number, since it uses less digits than its factorization.

1661988660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27699823 (or 27699821 counting only the distinct ones).

The product of its (nonzero) digits is 746496, while the sum is 51.

The square root of 1661988660 is about 40767.4951401236. The cubic root of 1661988660 is about 1184.5207839939.

The spelling of 1661988660 in words is "one billion, six hundred sixty-one million, nine hundred eighty-eight thousand, six hundred sixty".