31212130021 has 4 divisors (see below), whose sum is σ = 31213337344. Its totient is φ = 31210922700.

The previous prime is 31212129961. The next prime is 31212130049. The reversal of 31212130021 is 12003121213.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12003121213 = 4877 ⋅2461169.

It is a cyclic number.

It is not a de Polignac number, because 31212130021 - 2¹⁵ = 31212097253 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31212129977 and 31212130004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31212130321) 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, 564015 + ... + 616876.

It is an arithmetic number, because the mean of its divisors is an integer number (7803334336).

Almost surely, 2^31212130021 is an apocalyptic number.

It is an amenable number.

31212130021 is a deficient number, since it is larger than the sum of its proper divisors (1207323).

31212130021 is a wasteful number, since it uses less digits than its factorization.

31212130021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1207322.

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

Adding to 31212130021 its reverse (12003121213), we get a palindrome (43215251234).

The spelling of 31212130021 in words is "thirty-one billion, two hundred twelve million, one hundred thirty thousand, twenty-one".