21355413240 has 256 divisors, whose sum is σ = 77293440000. Its totient is φ = 4712655360.

The previous prime is 21355413239. The next prime is 21355413253. The reversal of 21355413240 is 4231455312.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21355413198 and 21355413207.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1184695 + ... + 1202585.

It is an arithmetic number, because the mean of its divisors is an integer number (301927500).

Almost surely, 2^21355413240 is an apocalyptic number.

21355413240 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 21355413240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38646720000).

21355413240 is an abundant number, since it is smaller than the sum of its proper divisors (55938026760).

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

21355413240 is a wasteful number, since it uses less digits than its factorization.

21355413240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17955 (or 17937 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 30.

Adding to 21355413240 its reverse (4231455312), we get a palindrome (25586868552).

The spelling of 21355413240 in words is "twenty-one billion, three hundred fifty-five million, four hundred thirteen thousand, two hundred forty".