215431 has 4 divisors (see below), whose sum is σ = 216664. Its totient is φ = 214200.

The previous prime is 215417. The next prime is 215443. The reversal of 215431 is 134512.

215431 is nontrivially palindromic in base 4.

215431 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 215431 - 2⁵ = 215399 is a prime.

It is a super-2 number, since 2×215431² = 92821031522, which contains 22 as substring.

It is a Duffinian number.

215431 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215461) 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, 300 + ... + 721.

It is an arithmetic number, because the mean of its divisors is an integer number (54166).

215431 is a Friedman number, since it can be written as 211*(4^5-3), using all its digits and the basic arithmetic operations.

2²¹⁵⁴³¹ is an apocalyptic number.

215431 is a deficient number, since it is larger than the sum of its proper divisors (1233).

215431 is a wasteful number, since it uses less digits than its factorization.

215431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1232.

The product of its digits is 120, while the sum is 16.

The square root of 215431 is about 464.1454513404. The cubic root of 215431 is about 59.9472684848.

Adding to 215431 its reverse (134512), we get a palindrome (349943).

It can be divided in two parts, 215 and 431, that multiplied together give a triangular number (92665 = T₄₃₀).

The spelling of 215431 in words is "two hundred fifteen thousand, four hundred thirty-one".