21435145520 has 80 divisors (see below), whose sum is σ = 50272094880. Its totient is φ = 8499351552.

The previous prime is 21435145493. The next prime is 21435145531. The reversal of 21435145520 is 2554153412.

It is a tau number, because it is divible by the number of its divisors (80).

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, 10863254 + ... + 10865226.

It is an arithmetic number, because the mean of its divisors is an integer number (628401186).

Almost surely, 2^21435145520 is an apocalyptic number.

21435145520 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 21435145520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25136047440).

21435145520 is an abundant number, since it is smaller than the sum of its proper divisors (28836949360).

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

21435145520 is a wasteful number, since it uses less digits than its factorization.

21435145520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3102 (or 3096 counting only the distinct ones).

The product of its (nonzero) digits is 24000, while the sum is 32.

Adding to 21435145520 its reverse (2554153412), we get a palindrome (23989298932).

The spelling of 21435145520 in words is "twenty-one billion, four hundred thirty-five million, one hundred forty-five thousand, five hundred twenty".