21520404052 has 24 divisors (see below), whose sum is σ = 43181023424. Its totient is φ = 9192984192.

The previous prime is 21520404041. The next prime is 21520404053. The reversal of 21520404052 is 25040402512.

It is a super-2 number, since 2×21520404052² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21520404053) 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, 1243173 + ... + 1260364.

Almost surely, 2^21520404052 is an apocalyptic number.

It is an amenable number.

21520404052 is an abundant number, since it is smaller than the sum of its proper divisors (21660619372).

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

21520404052 is a wasteful number, since it uses less digits than its factorization.

21520404052 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2503855 (or 2503853 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 25.

Adding to 21520404052 its reverse (25040402512), we get a palindrome (46560806564).

The spelling of 21520404052 in words is "twenty-one billion, five hundred twenty million, four hundred four thousand, fifty-two".