861780020 has 12 divisors (see below), whose sum is σ = 1809738084. Its totient is φ = 344712000.

The previous prime is 861780011. The next prime is 861780043. The reversal of 861780020 is 20087168.

It can be written as a sum of positive squares in 2 ways, for example, as 482153764 + 379626256 = 21958^2 + 19484^2 .

It is a hoax number, since the sum of its digits (32) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21544481 + ... + 21544520.

It is an arithmetic number, because the mean of its divisors is an integer number (150811507).

Almost surely, 2^861780020 is an apocalyptic number.

It is an amenable number.

861780020 is an abundant number, since it is smaller than the sum of its proper divisors (947958064).

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

861780020 is a wasteful number, since it uses less digits than its factorization.

861780020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43089010 (or 43089008 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 861780020 is about 29356.0899984995. The cubic root of 861780020 is about 951.6241911079.

The spelling of 861780020 in words is "eight hundred sixty-one million, seven hundred eighty thousand, twenty".