21020045504 has 56 divisors (see below), whose sum is σ = 43104669696. Its totient is φ = 10159776000.

The previous prime is 21020045503. The next prime is 21020045513. The reversal of 21020045504 is 40554002012.

It is a happy number.

It is a super-2 number, since 2×21020045504² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21020045504.

It is not an unprimeable number, because it can be changed into a prime (21020045503) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1960799 + ... + 1971489.

Almost surely, 2^21020045504 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21020045504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21552334848).

21020045504 is an abundant number, since it is smaller than the sum of its proper divisors (22084624192).

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

21020045504 is a wasteful number, since it uses less digits than its factorization.

21020045504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11725 (or 11715 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 23.

Adding to 21020045504 its reverse (40554002012), we get a palindrome (61574047516).

The spelling of 21020045504 in words is "twenty-one billion, twenty million, forty-five thousand, five hundred four".