21150520 has 16 divisors (see below), whose sum is σ = 47588760. Its totient is φ = 8460192.

The previous prime is 21150491. The next prime is 21150523. The reversal of 21150520 is 2505112.

It is a junction number, because it is equal to n+sod(n) for n = 21150494 and 21150503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21150523) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 264342 + ... + 264421.

Almost surely, 2^21150520 is an apocalyptic number.

21150520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21150520 is an abundant number, since it is smaller than the sum of its proper divisors (26438240).

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

21150520 is a wasteful number, since it uses less digits than its factorization.

21150520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 528774 (or 528770 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 16.

The square root of 21150520 is about 4598.9694497789. The cubic root of 21150520 is about 276.5500129168.

Adding to 21150520 its reverse (2505112), we get a palindrome (23655632).

The spelling of 21150520 in words is "twenty-one million, one hundred fifty thousand, five hundred twenty".