21355011520 has 28 divisors (see below), whose sum is σ = 50851621944. Its totient is φ = 8542004480.

The previous prime is 21355011511. The next prime is 21355011521. The reversal of 21355011520 is 2511055312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21355011521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33366886 + ... + 33367525.

Almost surely, 2^21355011520 is an apocalyptic number.

21355011520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21355011520 is an abundant number, since it is smaller than the sum of its proper divisors (29496610424).

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

21355011520 is an equidigital number, since it uses as much as digits as its factorization.

21355011520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66734428 (or 66734418 counting only the distinct ones).

The product of its (nonzero) digits is 1500, while the sum is 25.

Adding to 21355011520 its reverse (2511055312), we get a palindrome (23866066832).

The spelling of 21355011520 in words is "twenty-one billion, three hundred fifty-five million, eleven thousand, five hundred twenty".