21553424420 has 24 divisors (see below), whose sum is σ = 49376936448. Its totient is φ = 7837608800.

The previous prime is 21553424369. The next prime is 21553424423. The reversal of 21553424420 is 2442435512.

It is not an unprimeable number, because it can be changed into a prime (21553424423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48984836 + ... + 48985275.

It is an arithmetic number, because the mean of its divisors is an integer number (2057372352).

Almost surely, 2^21553424420 is an apocalyptic number.

21553424420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21553424420 is an abundant number, since it is smaller than the sum of its proper divisors (27823512028).

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

21553424420 is a wasteful number, since it uses less digits than its factorization.

21553424420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97970131 (or 97970129 counting only the distinct ones).

The product of its (nonzero) digits is 38400, while the sum is 32.

Adding to 21553424420 its reverse (2442435512), we get a palindrome (23995859932).

The spelling of 21553424420 in words is "twenty-one billion, five hundred fifty-three million, four hundred twenty-four thousand, four hundred twenty".