1661984020 has 24 divisors (see below), whose sum is σ = 3492720000. Its totient is φ = 664307232.

The previous prime is 1661984011. The next prime is 1661984029. The reversal of 1661984020 is 204891661.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1661984011) and next prime (1661984029).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661984029) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1720 + ... + 57679.

It is an arithmetic number, because the mean of its divisors is an integer number (145530000).

Almost surely, 2^1661984020 is an apocalyptic number.

1661984020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1661984020 is an abundant number, since it is smaller than the sum of its proper divisors (1830735980).

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

1661984020 is a wasteful number, since it uses less digits than its factorization.

1661984020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60807 (or 60805 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 1661984020 is about 40767.4382320008. The cubic root of 1661984020 is about 1184.5196816636.

The spelling of 1661984020 in words is "one billion, six hundred sixty-one million, nine hundred eighty-four thousand, twenty".