31311421 has 2 divisors, whose sum is σ = 31311422. Its totient is φ = 31311420.

The previous prime is 31311419. The next prime is 31311431. The reversal of 31311421 is 12411313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31304025 + 7396 = 5595^2 + 86^2 .

It is a cyclic number.

It is not a de Polignac number, because 31311421 - 2¹ = 31311419 is a prime.

Together with 31311419, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 31311395 and 31311404.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31311431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15655710 + 15655711.

It is an arithmetic number, because the mean of its divisors is an integer number (15655711).

Almost surely, 2^31311421 is an apocalyptic number.

It is an amenable number.

31311421 is a deficient number, since it is larger than the sum of its proper divisors (1).

31311421 is an equidigital number, since it uses as much as digits as its factorization.

31311421 is an evil number, because the sum of its binary digits is even.

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

The square root of 31311421 is about 5595.6609082395. The cubic root of 31311421 is about 315.1864890506.

Adding to 31311421 its reverse (12411313), we get a palindrome (43722734).

The spelling of 31311421 in words is "thirty-one million, three hundred eleven thousand, four hundred twenty-one".