21240572121520 has 80 divisors (see below), whose sum is σ = 49763939689728. Its totient is φ = 8430926549760.

The previous prime is 21240572121493. The next prime is 21240572121541. The reversal of 21240572121520 is 2512127504212.

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

It is a super-2 number, since 2×21240572121520² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 257211277 + ... + 257293843.

Almost surely, 2^{21240572121520} is an apocalyptic number.

21240572121520 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 21240572121520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24881969844864).

21240572121520 is an abundant number, since it is smaller than the sum of its proper divisors (28523367568208).

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

21240572121520 is a wasteful number, since it uses less digits than its factorization.

21240572121520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107258 (or 107252 counting only the distinct ones).

The product of its (nonzero) digits is 22400, while the sum is 34.

Adding to 21240572121520 its reverse (2512127504212), we get a palindrome (23752699625732).

The spelling of 21240572121520 in words is "twenty-one trillion, two hundred forty billion, five hundred seventy-two million, one hundred twenty-one thousand, five hundred twenty".