31231021021 has 12 divisors (see below), whose sum is σ = 32556668796. Its totient is φ = 29955999360.

The previous prime is 31231020949. The next prime is 31231021027. The reversal of 31231021021 is 12012013213.

It can be written as a sum of positive squares in 2 ways, for example, as 3010716900 + 28220304121 = 54870^2 + 167989^2 .

It is not a de Polignac number, because 31231021021 - 2¹⁵ = 31230988253 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31231020986 and 31231021004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31231021027) 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, 35206 + ... + 252391.

It is an arithmetic number, because the mean of its divisors is an integer number (2713055733).

Almost surely, 2^31231021021 is an apocalyptic number.

31231021021 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

31231021021 is a deficient number, since it is larger than the sum of its proper divisors (1325647775).

31231021021 is a wasteful number, since it uses less digits than its factorization.

31231021021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 287772 (or 287741 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 31231021021 its reverse (12012013213), we get a palindrome (43243034234).

It can be divided in two parts, 3123 and 1021021, that added together give a square (1024144 = 1012²).

The spelling of 31231021021 in words is "thirty-one billion, two hundred thirty-one million, twenty-one thousand, twenty-one".