20815515820 has 48 divisors (see below), whose sum is σ = 47726765856. Its totient is φ = 7562880000.

The previous prime is 20815515767. The next prime is 20815515839. The reversal of 20815515820 is 2851551802.

It is a self number, because there is not a number n which added to its sum of digits gives 20815515820.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 224830 + ... + 303610.

It is an arithmetic number, because the mean of its divisors is an integer number (994307622).

Almost surely, 2^20815515820 is an apocalyptic number.

20815515820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20815515820 is an abundant number, since it is smaller than the sum of its proper divisors (26911250036).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20815515820 is a wasteful number, since it uses less digits than its factorization.

20815515820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80002 (or 80000 counting only the distinct ones).

The product of its (nonzero) digits is 32000, while the sum is 37.

It can be divided in two parts, 20815 and 515820, that added together give a palindrome (536635).

The spelling of 20815515820 in words is "twenty billion, eight hundred fifteen million, five hundred fifteen thousand, eight hundred twenty".