20731313 has 4 divisors (see below), whose sum is σ = 21950820. Its totient is φ = 19511808.

The previous prime is 20731309. The next prime is 20731327. The reversal of 20731313 is 31313702.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15745024 + 4986289 = 3968^2 + 2233^2 .

It is a cyclic number.

It is not a de Polignac number, because 20731313 - 2² = 20731309 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20731813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 609728 + ... + 609761.

It is an arithmetic number, because the mean of its divisors is an integer number (5487705).

Almost surely, 2^20731313 is an apocalyptic number.

It is an amenable number.

20731313 is a deficient number, since it is larger than the sum of its proper divisors (1219507).

20731313 is a wasteful number, since it uses less digits than its factorization.

20731313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1219506.

The product of its (nonzero) digits is 378, while the sum is 20.

The square root of 20731313 is about 4553.1651628290. The cubic root of 20731313 is about 274.7107172871.

The spelling of 20731313 in words is "twenty million, seven hundred thirty-one thousand, three hundred thirteen".