31123421 has 4 divisors (see below), whose sum is σ = 35569632. Its totient is φ = 26677212.

The previous prime is 31123403. The next prime is 31123427. The reversal of 31123421 is 12432113.

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: 12432113 = 149 ⋅83437.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31123421 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31123421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31123427) 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, 2223095 + ... + 2223108.

It is an arithmetic number, because the mean of its divisors is an integer number (8892408).

Almost surely, 2^31123421 is an apocalyptic number.

It is an amenable number.

31123421 is a deficient number, since it is larger than the sum of its proper divisors (4446211).

31123421 is an equidigital number, since it uses as much as digits as its factorization.

31123421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4446210.

The product of its digits is 144, while the sum is 17.

The square root of 31123421 is about 5578.8368859467. The cubic root of 31123421 is about 314.5544081860.

Adding to 31123421 its reverse (12432113), we get a palindrome (43555534).

It can be divided in two parts, 311 and 23421, that added together give a palindrome (23732).

The spelling of 31123421 in words is "thirty-one million, one hundred twenty-three thousand, four hundred twenty-one".