861431 has 4 divisors (see below), whose sum is σ = 871200. Its totient is φ = 851664.

The previous prime is 861391. The next prime is 861433. The reversal of 861431 is 134168.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-861431 is a prime.

It is a super-2 number, since 2×861431² = 1484126735522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 861397 and 861406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861433) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4751 + ... + 4928.

It is an arithmetic number, because the mean of its divisors is an integer number (217800).

2⁸⁶¹⁴³¹ is an apocalyptic number.

861431 is a deficient number, since it is larger than the sum of its proper divisors (9769).

861431 is an equidigital number, since it uses as much as digits as its factorization.

861431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9768.

The product of its digits is 576, while the sum is 23.

The square root of 861431 is about 928.1330723555. The cubic root of 861431 is about 95.1495704829.

Adding to 861431 its reverse (134168), we get a palindrome (995599).

It can be divided in two parts, 861 and 431, that multiplied together give a triangular number (371091 = T₈₆₁).

The spelling of 861431 in words is "eight hundred sixty-one thousand, four hundred thirty-one".