20731237 has 4 divisors (see below), whose sum is σ = 20743020. Its totient is φ = 20719456.

The previous prime is 20731231. The next prime is 20731241. The reversal of 20731237 is 73213702.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 12152196 + 8579041 = 3486^2 + 2929^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20731237 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20731231) 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, 2662 + ... + 6967.

It is an arithmetic number, because the mean of its divisors is an integer number (5185755).

Almost surely, 2^20731237 is an apocalyptic number.

It is an amenable number.

20731237 is a deficient number, since it is larger than the sum of its proper divisors (11783).

20731237 is an equidigital number, since it uses as much as digits as its factorization.

20731237 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11782.

The product of its (nonzero) digits is 1764, while the sum is 25.

The square root of 20731237 is about 4553.1568169787. The cubic root of 20731237 is about 274.7103815946.

Adding to 20731237 its reverse (73213702), we get a palindrome (93944939).

The spelling of 20731237 in words is "twenty million, seven hundred thirty-one thousand, two hundred thirty-seven".