997821231 has 16 divisors (see below), whose sum is σ = 1454630400. Its totient is φ = 603384320.

The previous prime is 997821173. The next prime is 997821257. The reversal of 997821231 is 132128799.

It is not a de Polignac number, because 997821231 - 2²² = 993626927 is a prime.

It is a super-2 number, since 2×997821231² = 1991294418068710722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (997821281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18855 + ... + 48488.

It is an arithmetic number, because the mean of its divisors is an integer number (90914400).

Almost surely, 2^997821231 is an apocalyptic number.

997821231 is a deficient number, since it is larger than the sum of its proper divisors (456809169).

997821231 is a wasteful number, since it uses less digits than its factorization.

997821231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67806.

The product of its digits is 54432, while the sum is 42.

The square root of 997821231 is about 31588.3084542367. The cubic root of 997821231 is about 999.2732155790.

It can be divided in two parts, 997 and 821231, that added together give a palindrome (822228).

The spelling of 997821231 in words is "nine hundred ninety-seven million, eight hundred twenty-one thousand, two hundred thirty-one".