21245244240 has 320 divisors, whose sum is σ = 72944831232. Its totient is φ = 5072486400.

The previous prime is 21245244227. The next prime is 21245244257. The reversal of 21245244240 is 4244254212.

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 = 21245244198 and 21245244207.

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, 82666192 + ... + 82666448.

Almost surely, 2^21245244240 is an apocalyptic number.

21245244240 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 21245244240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36472415616).

21245244240 is an abundant number, since it is smaller than the sum of its proper divisors (51699586992).

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

21245244240 is a wasteful number, since it uses less digits than its factorization.

21245244240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 638 (or 632 counting only the distinct ones).

The product of its (nonzero) digits is 20480, while the sum is 30.

Adding to 21245244240 its reverse (4244254212), we get a palindrome (25489498452).

The spelling of 21245244240 in words is "twenty-one billion, two hundred forty-five million, two hundred forty-four thousand, two hundred forty".