20505115331 has 4 divisors (see below), whose sum is σ = 20508594912. Its totient is φ = 20501635752.

The previous prime is 20505115307. The next prime is 20505115333. The reversal of 20505115331 is 13351150502.

It is a happy number.

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 20505115331 - 2³⁴ = 3325246147 is a prime.

It is a super-2 number, since 2×20505115331² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20505115331.

It is not an unprimeable number, because it can be changed into a prime (20505115333) 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, 1730936 + ... + 1742741.

It is an arithmetic number, because the mean of its divisors is an integer number (5127148728).

Almost surely, 2^20505115331 is an apocalyptic number.

20505115331 is a deficient number, since it is larger than the sum of its proper divisors (3479581).

20505115331 is an equidigital number, since it uses as much as digits as its factorization.

20505115331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3479580.

The product of its (nonzero) digits is 2250, while the sum is 26.

Adding to 20505115331 its reverse (13351150502), we get a palindrome (33856265833).

The spelling of 20505115331 in words is "twenty billion, five hundred five million, one hundred fifteen thousand, three hundred thirty-one".