31028131921 has 4 divisors (see below), whose sum is σ = 31063113792. Its totient is φ = 30993150052.

The previous prime is 31028131913. The next prime is 31028131933. The reversal of 31028131921 is 12913182013.

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: 12913182013 = 71 ⋅181875803.

It is a cyclic number.

It is not a de Polignac number, because 31028131921 - 2³ = 31028131913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31028131951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17489605 + ... + 17491378.

It is an arithmetic number, because the mean of its divisors is an integer number (7765778448).

Almost surely, 2^31028131921 is an apocalyptic number.

It is an amenable number.

31028131921 is a deficient number, since it is larger than the sum of its proper divisors (34981871).

31028131921 is an equidigital number, since it uses as much as digits as its factorization.

31028131921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34981870.

The product of its (nonzero) digits is 2592, while the sum is 31.

The spelling of 31028131921 in words is "thirty-one billion, twenty-eight million, one hundred thirty-one thousand, nine hundred twenty-one".