820731 has 8 divisors (see below), whose sum is σ = 1108480. Its totient is φ = 540072.

The previous prime is 820723. The next prime is 820733. The reversal of 820731 is 137028.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 820731 - 2³ = 820723 is a prime.

It is a super-2 number, since 2×820731² = 1347198748722, which contains 22 as substring.

It is a Duffinian number.

820731 is a lucky number.

It is a nialpdrome in base 7.

It is a junction number, because it is equal to n+sod(n) for n = 820698 and 820707.

It is not an unprimeable number, because it can be changed into a prime (820733) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1495 + ... + 1968.

It is an arithmetic number, because the mean of its divisors is an integer number (138560).

2⁸²⁰⁷³¹ is an apocalyptic number.

820731 is a deficient number, since it is larger than the sum of its proper divisors (287749).

820731 is a wasteful number, since it uses less digits than its factorization.

820731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3545.

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 820731 is about 905.9420511269. The cubic root of 820731 is about 93.6268213368.

Adding to 820731 its reverse (137028), we get a palindrome (957759).

It can be divided in two parts, 820 and 731, that added together give a palindrome (1551).

The spelling of 820731 in words is "eight hundred twenty thousand, seven hundred thirty-one".