21401003520 has 800 divisors, whose sum is σ = 87590831328. Its totient is φ = 4947443712.

The previous prime is 21401003513. The next prime is 21401003539. The reversal of 21401003520 is 2530010412.

21401003520 is a `hidden beast` number, since 2 + 1 + 40 + 100 + 3 + 520 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21401003493 and 21401003502.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 45826327 + ... + 45826793.

Almost surely, 2^21401003520 is an apocalyptic number.

21401003520 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 21401003520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43795415664).

21401003520 is an abundant number, since it is smaller than the sum of its proper divisors (66189827808).

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

21401003520 is a wasteful number, since it uses less digits than its factorization.

21401003520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 532 (or 507 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

Adding to 21401003520 its reverse (2530010412), we get a palindrome (23931013932).

The spelling of 21401003520 in words is "twenty-one billion, four hundred one million, three thousand, five hundred twenty".