1661831990 has 32 divisors (see below), whose sum is σ = 3681599040. Its totient is φ = 525942144.

The previous prime is 1661831989. The next prime is 1661831993. The reversal of 1661831990 is 991381661.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661831993) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 912185 + ... + 914004.

It is an arithmetic number, because the mean of its divisors is an integer number (115049970).

Almost surely, 2^1661831990 is an apocalyptic number.

1661831990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1661831990 is an abundant number, since it is smaller than the sum of its proper divisors (2019767050).

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

1661831990 is a wasteful number, since it uses less digits than its factorization.

1661831990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1826216.

The product of its (nonzero) digits is 69984, while the sum is 44.

The square root of 1661831990 is about 40765.5735885073. The cubic root of 1661831990 is about 1184.4835625801.

The spelling of 1661831990 in words is "one billion, six hundred sixty-one million, eight hundred thirty-one thousand, nine hundred ninety".