31230320021 has 4 divisors (see below), whose sum is σ = 31230788832. Its totient is φ = 31229851212.

The previous prime is 31230319957. The next prime is 31230320047. The reversal of 31230320021 is 12002303213.

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: 12002303213 = 16561 ⋅724733.

It is a cyclic number.

It is not a de Polignac number, because 31230320021 - 2⁶ = 31230319957 is a prime.

It is a super-2 number, since 2×31230320021² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31230320321) 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, 113795 + ... + 274608.

It is an arithmetic number, because the mean of its divisors is an integer number (7807697208).

Almost surely, 2^31230320021 is an apocalyptic number.

It is an amenable number.

31230320021 is a deficient number, since it is larger than the sum of its proper divisors (468811).

31230320021 is an equidigital number, since it uses as much as digits as its factorization.

31230320021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 468810.

The product of its (nonzero) digits is 216, while the sum is 17.

Adding to 31230320021 its reverse (12002303213), we get a palindrome (43232623234).

The spelling of 31230320021 in words is "thirty-one billion, two hundred thirty million, three hundred twenty thousand, twenty-one".