20315131 has 4 divisors (see below), whose sum is σ = 20810664. Its totient is φ = 19819600.

The previous prime is 20315129. The next prime is 20315143. The reversal of 20315131 is 13151302.

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

It is a cyclic number.

It is not a de Polignac number, because 20315131 - 2¹ = 20315129 is a prime.

It is a super-2 number, since 2×20315131² = 825409095094322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20315171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 247705 + ... + 247786.

It is an arithmetic number, because the mean of its divisors is an integer number (5202666).

Almost surely, 2^20315131 is an apocalyptic number.

20315131 is a deficient number, since it is larger than the sum of its proper divisors (495533).

20315131 is an equidigital number, since it uses as much as digits as its factorization.

20315131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 495532.

The product of its (nonzero) digits is 90, while the sum is 16.

The square root of 20315131 is about 4507.2309681222. The cubic root of 20315131 is about 272.8600005836.

Adding to 20315131 its reverse (13151302), we get a palindrome (33466433).

The spelling of 20315131 in words is "twenty million, three hundred fifteen thousand, one hundred thirty-one".