31312021 has 8 divisors (see below), whose sum is σ = 33766040.
Its totient is φ = 28864512.
The previous prime is 31312007. The next prime is 31312033. The reversal of 31312021 is 12021313.
It can be written as a sum of positive squares in 4 ways, for example, as 9090225 + 22221796 = 3015^2 + 4714^2
It is a sphenic number, since it is the product of 3 distinct primes.
It is a cyclic number.
It is not a de Polignac number, because 31312021 - 25 = 31311989 is a prime.
It is a Harshad number since it is a multiple of its sum of digits (13).
It is a Duffinian number.
It is a junction number, because it is equal to n+sod(n) for n = 31311992 and 31312010.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (31312051) by changing a digit.
It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13945 + ... + 16033.
It is an arithmetic number, because the mean of its divisors is an integer number (4220755).
Almost surely, 231312021 is an apocalyptic number.
It is an amenable number.
31312021 is a deficient number, since it is larger than the sum of its proper divisors (2454019).
31312021 is a wasteful number, since it uses less digits than its factorization.
31312021 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 3255.
The product of its (nonzero) digits is 36, while the sum is 13.
The square root of 31312021 is about 5595.7145209526.
The cubic root of 31312021 is about 315.1885022743.
Adding to 31312021 its reverse (12021313), we get a palindrome (43333334).
The spelling of 31312021 in words is "thirty-one million, three hundred twelve thousand, twenty-one".