21142111520 has 192 divisors, whose sum is σ = 53550637056. Its totient is φ = 7869312000.

The previous prime is 21142111517. The next prime is 21142111553. The reversal of 21142111520 is 2511124112.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21142111492 and 21142111501.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 43412717 + ... + 43413203.

It is an arithmetic number, because the mean of its divisors is an integer number (278909568).

Almost surely, 2^21142111520 is an apocalyptic number.

21142111520 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 21142111520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26775318528).

21142111520 is an abundant number, since it is smaller than the sum of its proper divisors (32408525536).

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

21142111520 is a wasteful number, since it uses less digits than its factorization.

21142111520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 823 (or 815 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 20.

Adding to 21142111520 its reverse (2511124112), we get a palindrome (23653235632).

The spelling of 21142111520 in words is "twenty-one billion, one hundred forty-two million, one hundred eleven thousand, five hundred twenty".