21236306420 has 24 divisors (see below), whose sum is σ = 50967135744. Its totient is φ = 7281019296.

The previous prime is 21236306417. The next prime is 21236306453. The reversal of 21236306420 is 2460363212.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 75843812 + ... + 75844091.

It is an arithmetic number, because the mean of its divisors is an integer number (2123630656).

Almost surely, 2^21236306420 is an apocalyptic number.

21236306420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21236306420 is an abundant number, since it is smaller than the sum of its proper divisors (29730829324).

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

21236306420 is a wasteful number, since it uses less digits than its factorization.

21236306420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151687919 (or 151687917 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 29.

Adding to 21236306420 its reverse (2460363212), we get a palindrome (23696669632).

The spelling of 21236306420 in words is "twenty-one billion, two hundred thirty-six million, three hundred six thousand, four hundred twenty".