20130731 has 4 divisors (see below), whose sum is σ = 20215200. Its totient is φ = 20046264.

The previous prime is 20130707. The next prime is 20130739. The reversal of 20130731 is 13703102.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20130731 is a prime.

It is a super-2 number, since 2×20130731² = 810492661188722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20130739) 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, 41876 + ... + 42353.

It is an arithmetic number, because the mean of its divisors is an integer number (5053800).

Almost surely, 2^20130731 is an apocalyptic number.

20130731 is a deficient number, since it is larger than the sum of its proper divisors (84469).

20130731 is an equidigital number, since it uses as much as digits as its factorization.

20130731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84468.

The product of its (nonzero) digits is 126, while the sum is 17.

The square root of 20130731 is about 4486.7283180509. The cubic root of 20130731 is about 272.0319085620.

Adding to 20130731 its reverse (13703102), we get a palindrome (33833833).

The spelling of 20130731 in words is "twenty million, one hundred thirty thousand, seven hundred thirty-one".