21520523212540 has 72 divisors (see below), whose sum is σ = 50374708072416. Its totient is φ = 7715424393600.

The previous prime is 21520523212423. The next prime is 21520523212543. The reversal of 21520523212540 is 4521232502512.

It is a junction number, because it is equal to n+sod(n) for n = 21520523212496 and 21520523212505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21520523212543) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 62453379 + ... + 62797018.

It is an arithmetic number, because the mean of its divisors is an integer number (699648723228).

Almost surely, 2^{21520523212540} is an apocalyptic number.

21520523212540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21520523212540 is an abundant number, since it is smaller than the sum of its proper divisors (28854184859876).

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

21520523212540 is a wasteful number, since it uses less digits than its factorization.

21520523212540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125250499 (or 125250486 counting only the distinct ones).

The product of its (nonzero) digits is 48000, while the sum is 34.

The spelling of 21520523212540 in words is "twenty-one trillion, five hundred twenty billion, five hundred twenty-three million, two hundred twelve thousand, five hundred forty".