861541821 has 12 divisors (see below), whose sum is σ = 1422227872. Its totient is φ = 492309576.

The previous prime is 861541789. The next prime is 861541823. The reversal of 861541821 is 128145168.

861541821 is a `hidden beast` number, since 8 + 615 + 4 + 18 + 21 = 666.

It is not a de Polignac number, because 861541821 - 2⁵ = 861541789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861541823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6837571 + ... + 6837696.

Almost surely, 2^861541821 is an apocalyptic number.

It is an amenable number.

861541821 is a deficient number, since it is larger than the sum of its proper divisors (560686051).

861541821 is a wasteful number, since it uses less digits than its factorization.

861541821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13675280 (or 13675277 counting only the distinct ones).

The product of its digits is 15360, while the sum is 36.

The square root of 861541821 is about 29352.0326553375. The cubic root of 861541821 is about 951.5365056146.

Adding to 861541821 its reverse (128145168), we get a palindrome (989686989).

The spelling of 861541821 in words is "eight hundred sixty-one million, five hundred forty-one thousand, eight hundred twenty-one".