1661816400 has 60 divisors (see below), whose sum is σ = 5323355712. Its totient is φ = 443150720.

The previous prime is 1661816389. The next prime is 1661816417. The reversal of 1661816400 is 46181661.

It is a tau number, because it is divible by the number of its divisors (60).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 691224 + ... + 693623.

Almost surely, 2^1661816400 is an apocalyptic number.

1661816400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1661816400 is an abundant number, since it is smaller than the sum of its proper divisors (3661539312).

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

1661816400 is a wasteful number, since it uses less digits than its factorization.

1661816400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1384868 (or 1384857 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 1661816400 is about 40765.3823727927. The cubic root of 1661816400 is about 1184.4798586043.

The spelling of 1661816400 in words is "one billion, six hundred sixty-one million, eight hundred sixteen thousand, four hundred".