1861405680 has 80 divisors (see below), whose sum is σ = 6074075520. Its totient is φ = 470248704.

The previous prime is 1861405673. The next prime is 1861405727. The reversal of 1861405680 is 865041681.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×1861405680² = 6929662211072524800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 199542 + ... + 208661.

It is an arithmetic number, because the mean of its divisors is an integer number (75925944).

Almost surely, 2^1861405680 is an apocalyptic number.

1861405680 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1861405680 is an abundant number, since it is smaller than the sum of its proper divisors (4212669840).

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

1861405680 is a wasteful number, since it uses less digits than its factorization.

1861405680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 408238 (or 408232 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 39.

The square root of 1861405680 is about 43144.0109401062. The cubic root of 1861405680 is about 1230.1186745169.

The spelling of 1861405680 in words is "one billion, eight hundred sixty-one million, four hundred five thousand, six hundred eighty".