31231021 has 4 divisors (see below), whose sum is σ = 31248000. Its totient is φ = 31214044.

The previous prime is 31231009. The next prime is 31231027. The reversal of 31231021 is 12013213.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 31231021 - 2¹¹ = 31228973 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31230992 and 31231010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31231027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5341 + ... + 9538.

It is an arithmetic number, because the mean of its divisors is an integer number (7812000).

Almost surely, 2^31231021 is an apocalyptic number.

It is an amenable number.

31231021 is a deficient number, since it is larger than the sum of its proper divisors (16979).

31231021 is a wasteful number, since it uses less digits than its factorization.

31231021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16978.

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 31231021 is about 5588.4721525655. The cubic root of 31231021 is about 314.9164841162.

Adding to 31231021 its reverse (12013213), we get a palindrome (43244234).

The spelling of 31231021 in words is "thirty-one million, two hundred thirty-one thousand, twenty-one".