21523040440 has 64 divisors (see below), whose sum is σ = 52894516320. Its totient is φ = 7816896000.

The previous prime is 21523040431. The next prime is 21523040467. The reversal of 21523040440 is 4404032512.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 331450 + ... + 391030.

Almost surely, 2^21523040440 is an apocalyptic number.

21523040440 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 21523040440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26447258160).

21523040440 is an abundant number, since it is smaller than the sum of its proper divisors (31371475880).

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

21523040440 is a wasteful number, since it uses less digits than its factorization.

21523040440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60424 (or 60420 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 25.

Adding to 21523040440 its reverse (4404032512), we get a palindrome (25927072952).

The spelling of 21523040440 in words is "twenty-one billion, five hundred twenty-three million, forty thousand, four hundred forty".