861421 has 4 divisors (see below), whose sum is σ = 939744. Its totient is φ = 783100.

The previous prime is 861391. The next prime is 861433. The reversal of 861421 is 124168.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 861421 - 2⁷ = 861293 is a prime.

It is a super-3 number, since 3×861421³ = 1917642381933364383, which contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 861392 and 861401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39145 + ... + 39166.

It is an arithmetic number, because the mean of its divisors is an integer number (234936).

2⁸⁶¹⁴²¹ is an apocalyptic number.

It is an amenable number.

861421 is a deficient number, since it is larger than the sum of its proper divisors (78323).

861421 is a wasteful number, since it uses less digits than its factorization.

861421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78322.

The product of its digits is 384, while the sum is 22.

The square root of 861421 is about 928.1276851813. The cubic root of 861421 is about 95.1492022974.

Adding to 861421 its reverse (124168), we get a palindrome (985589).

The spelling of 861421 in words is "eight hundred sixty-one thousand, four hundred twenty-one".