21263211720 has 512 divisors, whose sum is σ = 78643353600. Its totient is φ = 5087232000.

The previous prime is 21263211709. The next prime is 21263211727. The reversal of 21263211720 is 2711236212.

21263211720 is a `hidden beast` number, since 2 + 1 + 2 + 632 + 1 + 1 + 7 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21263211727) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 35379420 + ... + 35380020.

It is an arithmetic number, because the mean of its divisors is an integer number (153600300).

Almost surely, 2^21263211720 is an apocalyptic number.

21263211720 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 21263211720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39321676800).

21263211720 is an abundant number, since it is smaller than the sum of its proper divisors (57380141880).

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

21263211720 is a wasteful number, since it uses less digits than its factorization.

21263211720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 726 (or 716 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

Adding to 21263211720 its reverse (2711236212), we get a palindrome (23974447932).

The spelling of 21263211720 in words is "twenty-one billion, two hundred sixty-three million, two hundred eleven thousand, seven hundred twenty".