21530625 has 20 divisors (see below), whose sum is σ = 35876016. Its totient is φ = 11482000.

The previous prime is 21530623. The next prime is 21530627. The reversal of 21530625 is 52603512.

It is an interprime number because it is at equal distance from previous prime (21530623) and next prime (21530627).

It is not a de Polignac number, because 21530625 - 2¹ = 21530623 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21530595 and 21530604.

It is not an unprimeable number, because it can be changed into a prime (21530623) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3867 + ... + 7616.

Almost surely, 2^21530625 is an apocalyptic number.

21530625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21530625 is a deficient number, since it is larger than the sum of its proper divisors (14345391).

21530625 is an equidigital number, since it uses as much as digits as its factorization.

21530625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11506 (or 11491 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 24.

The square root of 21530625 is about 4640.1104512716. The cubic root of 21530625 is about 278.1968526218.

It can be divided in two parts, 21530 and 625, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 21530625 in words is "twenty-one million, five hundred thirty thousand, six hundred twenty-five".