21000525 has 96 divisors (see below), whose sum is σ = 45497088. Its totient is φ = 8294400.

The previous prime is 21000517. The next prime is 21000527. The reversal of 21000525 is 52500012.

It is not a de Polignac number, because 21000525 - 2³ = 21000517 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000527) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 115935 + ... + 116115.

It is an arithmetic number, because the mean of its divisors is an integer number (473928).

Almost surely, 2^21000525 is an apocalyptic number.

21000525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21000525 is an abundant number, since it is smaller than the sum of its proper divisors (24496563).

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

21000525 is a wasteful number, since it uses less digits than its factorization.

21000525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 231 (or 226 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 15.

The square root of 21000525 is about 4582.6329767940. The cubic root of 21000525 is about 275.8947167224.

Adding to 21000525 its reverse (52500012), we get a palindrome (73500537).

The spelling of 21000525 in words is "twenty-one million, five hundred twenty-five", and thus it is an aban number.