231221997 has 12 divisors (see below), whose sum is σ = 335855520. Its totient is φ = 153285768.

The previous prime is 231221983. The next prime is 231222011. The reversal of 231221997 is 799122132.

It is an interprime number because it is at equal distance from previous prime (231221983) and next prime (231222011).

It is not a de Polignac number, because 231221997 - 2⁶ = 231221933 is a prime.

It is a super-2 number, since 2×231221997² = 106927223793336018, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231221957) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 70153 + ... + 73374.

It is an arithmetic number, because the mean of its divisors is an integer number (27987960).

Almost surely, 2^231221997 is an apocalyptic number.

It is an amenable number.

231221997 is a deficient number, since it is larger than the sum of its proper divisors (104633523).

231221997 is a wasteful number, since it uses less digits than its factorization.

231221997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143712 (or 143709 counting only the distinct ones).

The product of its digits is 13608, while the sum is 36.

The square root of 231221997 is about 15205.9855649017. The cubic root of 231221997 is about 613.7757362318.

The spelling of 231221997 in words is "two hundred thirty-one million, two hundred twenty-one thousand, nine hundred ninety-seven".