861788421 has 12 divisors (see below), whose sum is σ = 1340559948. Its totient is φ = 530331264.

The previous prime is 861788407. The next prime is 861788461. The reversal of 861788421 is 124887168.

861788421 is a `hidden beast` number, since 8 + 617 + 8 + 8 + 4 + 21 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 364275396 + 497513025 = 19086^2 + 22305^2 .

It is not a de Polignac number, because 861788421 - 2¹⁰ = 861787397 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861788461) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3682740 + ... + 3682973.

It is an arithmetic number, because the mean of its divisors is an integer number (111713329).

Almost surely, 2^861788421 is an apocalyptic number.

It is an amenable number.

861788421 is a deficient number, since it is larger than the sum of its proper divisors (478771527).

861788421 is a wasteful number, since it uses less digits than its factorization.

861788421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7365732 (or 7365729 counting only the distinct ones).

The product of its digits is 172032, while the sum is 45.

The square root of 861788421 is about 29356.2330860075. The cubic root of 861788421 is about 951.6272833776.

The spelling of 861788421 in words is "eight hundred sixty-one million, seven hundred eighty-eight thousand, four hundred twenty-one".