21803787520 has 36 divisors (see below), whose sum is σ = 52226887860. Its totient is φ = 8721514496.

The previous prime is 21803787491. The next prime is 21803787521. The reversal of 21803787520 is 2578730812.

It can be written as a sum of positive squares in 2 ways, for example, as 15503238144 + 6300549376 = 124512^2 + 79376^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21803787521) 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, 8515825 + ... + 8518384.

It is an arithmetic number, because the mean of its divisors is an integer number (1450746885).

Almost surely, 2^21803787520 is an apocalyptic number.

21803787520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21803787520 is an abundant number, since it is smaller than the sum of its proper divisors (30423100340).

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

21803787520 is an equidigital number, since it uses as much as digits as its factorization.

21803787520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17034230 (or 17034216 counting only the distinct ones).

The product of its (nonzero) digits is 188160, while the sum is 43.

The spelling of 21803787520 in words is "twenty-one billion, eight hundred three million, seven hundred eighty-seven thousand, five hundred twenty".