1661815782 has 48 divisors (see below), whose sum is σ = 3934249488. Its totient is φ = 502770240.

The previous prime is 1661815777. The next prime is 1661815783. The reversal of 1661815782 is 2875181661.

1661815782 is a `hidden beast` number, since 1 + 66 + 18 + 1 + 578 + 2 = 666.

1661815782 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661815783) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 122868 + ... + 135720.

It is an arithmetic number, because the mean of its divisors is an integer number (81963531).

Almost surely, 2^1661815782 is an apocalyptic number.

1661815782 is an abundant number, since it is smaller than the sum of its proper divisors (2272433706).

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

1661815782 is a wasteful number, since it uses less digits than its factorization.

1661815782 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13525 (or 13522 counting only the distinct ones).

The product of its digits is 161280, while the sum is 45.

The square root of 1661815782 is about 40765.3747928312. The cubic root of 1661815782 is about 1184.4797117753.

It can be divided in two parts, 16618 and 15782, that added together give a square (32400 = 180²).

The spelling of 1661815782 in words is "one billion, six hundred sixty-one million, eight hundred fifteen thousand, seven hundred eighty-two".