21066520 has 32 divisors (see below), whose sum is σ = 47592720. Its totient is φ = 8392320.

The previous prime is 21066511. The next prime is 21066523. The reversal of 21066520 is 2566012.

It is a junction number, because it is equal to n+sod(n) for n = 21066491 and 21066500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21066523) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10390 + ... + 12250.

Almost surely, 2^21066520 is an apocalyptic number.

21066520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21066520 is an abundant number, since it is smaller than the sum of its proper divisors (26526200).

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

21066520 is a wasteful number, since it uses less digits than its factorization.

21066520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2155 (or 2151 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21066520 is about 4589.8278834832. The cubic root of 21066520 is about 276.1834179537.

The spelling of 21066520 in words is "twenty-one million, sixty-six thousand, five hundred twenty".