21525320 has 32 divisors (see below), whose sum is σ = 48886200. Its totient is φ = 8529408.

The previous prime is 21525319. The next prime is 21525331. The reversal of 21525320 is 2352512.

It can be written as a sum of positive squares in 4 ways, for example, as 18335524 + 3189796 = 4282^2 + 1786^2 .

It is a super-2 number, since 2×21525320² = 926678802204800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21525292 and 21525301.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1892 + ... + 6828.

Almost surely, 2^21525320 is an apocalyptic number.

21525320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21525320 is an abundant number, since it is smaller than the sum of its proper divisors (27360880).

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

21525320 is a wasteful number, since it uses less digits than its factorization.

21525320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5057 (or 5053 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 20.

The square root of 21525320 is about 4639.5387701796. The cubic root of 21525320 is about 278.1740021390.

Adding to 21525320 its reverse (2352512), we get a palindrome (23877832).

The spelling of 21525320 in words is "twenty-one million, five hundred twenty-five thousand, three hundred twenty".