31232131220221 has 4 divisors (see below), whose sum is σ = 31232281625244. Its totient is φ = 31231980815200.

The previous prime is 31232131220201. The next prime is 31232131220287. The reversal of 31232131220221 is 12202213123213.

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

It can be written as a sum of positive squares in 2 ways, for example, as 22710466802500 + 8521664417721 = 4765550^2 + 2919189^2 .

It is a cyclic number.

It is not a de Polignac number, because 31232131220221 - 2⁷ = 31232131220093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31232131220201) 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, 74890600 + ... + 75306481.

It is an arithmetic number, because the mean of its divisors is an integer number (7808070406311).

Almost surely, 2^{31232131220221} is an apocalyptic number.

It is an amenable number.

31232131220221 is a deficient number, since it is larger than the sum of its proper divisors (150405023).

31232131220221 is a wasteful number, since it uses less digits than its factorization.

31232131220221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150405022.

The product of its (nonzero) digits is 1728, while the sum is 25.

Adding to 31232131220221 its reverse (12202213123213), we get a palindrome (43434344343434).

It can be divided in two parts, 3123213 and 1220221, that added together give a palindrome (4343434).

The spelling of 31232131220221 in words is "thirty-one trillion, two hundred thirty-two billion, one hundred thirty-one million, two hundred twenty thousand, two hundred twenty-one".