1661011800 has 240 divisors, whose sum is σ = 6012178440. Its totient is φ = 379330560.

The previous prime is 1661011727. The next prime is 1661011813. The reversal of 1661011800 is 81101661.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 1440024 + ... + 1441176.

Almost surely, 2^1661011800 is an apocalyptic number.

1661011800 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1661011800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3006089220).

1661011800 is an abundant number, since it is smaller than the sum of its proper divisors (4351166640).

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

1661011800 is a wasteful number, since it uses less digits than its factorization.

1661011800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1200 (or 1170 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 24.

The square root of 1661011800 is about 40755.5125105795. The cubic root of 1661011800 is about 1184.2886649311.

The spelling of 1661011800 in words is "one billion, six hundred sixty-one million, eleven thousand, eight hundred".