21000625 has 10 divisors (see below), whose sum is σ = 26243162. Its totient is φ = 16800000.

The previous prime is 21000613. The next prime is 21000673. The reversal of 21000625 is 52600012.

It is a happy number.

It can be written as a sum of positive squares in 5 ways, for example, as 15374241 + 5626384 = 3921^2 + 2372^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21000625 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21000599 and 21000608.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 16176 + ... + 17425.

Almost surely, 2^21000625 is an apocalyptic number.

21000625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21000625 is a deficient number, since it is larger than the sum of its proper divisors (5242537).

21000625 is an frugal number, since it uses more digits than its factorization.

21000625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33621 (or 33606 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21000625 is about 4582.6438875392. The cubic root of 21000625 is about 275.8951546389.

Adding to 21000625 its reverse (52600012), we get a palindrome (73600637).

The spelling of 21000625 in words is "twenty-one million, six hundred twenty-five", and thus it is an aban number.