31340021 has 4 divisors (see below), whose sum is σ = 31663212. Its totient is φ = 31016832.

The previous prime is 31340009. The next prime is 31340051. The reversal of 31340021 is 12004313.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12004313 = 223 ⋅53831.

It can be written as a sum of positive squares in 2 ways, for example, as 7623121 + 23716900 = 2761^2 + 4870^2 .

It is a cyclic number.

It is not a de Polignac number, because 31340021 - 2¹⁴ = 31323637 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 31339978 and 31340005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31340051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 161450 + ... + 161643.

It is an arithmetic number, because the mean of its divisors is an integer number (7915803).

Almost surely, 2^31340021 is an apocalyptic number.

It is an amenable number.

31340021 is a deficient number, since it is larger than the sum of its proper divisors (323191).

31340021 is an equidigital number, since it uses as much as digits as its factorization.

31340021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 323190.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 31340021 is about 5598.2158765092. The cubic root of 31340021 is about 315.2824241239.

Adding to 31340021 its reverse (12004313), we get a palindrome (43344334).

The spelling of 31340021 in words is "thirty-one million, three hundred forty thousand, twenty-one".