21200520 has 64 divisors (see below), whose sum is σ = 69387840. Its totient is φ = 5139200.

The previous prime is 21200507. The next prime is 21200521. The reversal of 21200520 is 2500212.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21200496 and 21200505.

It is not an unprimeable number, because it can be changed into a prime (21200521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6711 + ... + 9350.

It is an arithmetic number, because the mean of its divisors is an integer number (1084185).

Almost surely, 2^21200520 is an apocalyptic number.

21200520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21200520 is an abundant number, since it is smaller than the sum of its proper divisors (48187320).

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

21200520 is a wasteful number, since it uses less digits than its factorization.

21200520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16086 (or 16082 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 12.

The square root of 21200520 is about 4604.4022413338. The cubic root of 21200520 is about 276.7677635730.

Adding to 21200520 its reverse (2500212), we get a palindrome (23700732).

The spelling of 21200520 in words is "twenty-one million, two hundred thousand, five hundred twenty".