21263423220 has 288 divisors, whose sum is σ = 71263116288. Its totient is φ = 5099314176.

The previous prime is 21263423197. The next prime is 21263423257. The reversal of 21263423220 is 2232436212.

It is a happy number.

21263423220 is a `hidden beast` number, since 2 + 1 + 2 + 634 + 2 + 3 + 2 + 20 = 666.

It is a congruent number.

It is an unprimeable number.

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 95 ways as a sum of consecutive naturals, for example, 43661817 + ... + 43662303.

It is an arithmetic number, because the mean of its divisors is an integer number (247441376).

Almost surely, 2^21263423220 is an apocalyptic number.

21263423220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21263423220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35631558144).

21263423220 is an abundant number, since it is smaller than the sum of its proper divisors (49999693068).

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

21263423220 is a wasteful number, since it uses less digits than its factorization.

21263423220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 959 (or 954 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 27.

Adding to 21263423220 its reverse (2232436212), we get a palindrome (23495859432).

The spelling of 21263423220 in words is "twenty-one billion, two hundred sixty-three million, four hundred twenty-three thousand, two hundred twenty".