21520506700 has 144 divisors (see below), whose sum is σ = 59577686784. Its totient is φ = 6551596800.

The previous prime is 21520506643. The next prime is 21520506701. The reversal of 21520506700 is 760502512.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is not an unprimeable number, because it can be changed into a prime (21520506701) 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 47 ways as a sum of consecutive naturals, for example, 298602 + ... + 363598.

It is an arithmetic number, because the mean of its divisors is an integer number (413733936).

Almost surely, 2^21520506700 is an apocalyptic number.

21520506700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21520506700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29788843392).

21520506700 is an abundant number, since it is smaller than the sum of its proper divisors (38057180084).

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

21520506700 is a wasteful number, since it uses less digits than its factorization.

21520506700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65072 (or 65065 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 28.

The spelling of 21520506700 in words is "twenty-one billion, five hundred twenty million, five hundred six thousand, seven hundred".