21502025 has 12 divisors (see below), whose sum is σ = 28231452. Its totient is φ = 16189440.

The previous prime is 21502007. The next prime is 21502027. The reversal of 21502025 is 52020512.

21502025 = 498² + 499² + ... + 572².

It can be written as a sum of positive squares in 6 ways, for example, as 256 + 21501769 = 16^2 + 4637^2 .

It is not a de Polignac number, because 21502025 - 2¹² = 21497929 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21501994 and 21502012.

It is not an unprimeable number, because it can be changed into a prime (21502027) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 24872 + ... + 25721.

It is an arithmetic number, because the mean of its divisors is an integer number (2352621).

Almost surely, 2^21502025 is an apocalyptic number.

21502025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21502025 is a deficient number, since it is larger than the sum of its proper divisors (6729427).

21502025 is a wasteful number, since it uses less digits than its factorization.

21502025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50620 (or 50615 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 17.

The square root of 21502025 is about 4637.0276039722. The cubic root of 21502025 is about 278.0736179962.

Adding to 21502025 its reverse (52020512), we get a palindrome (73522537).

The spelling of 21502025 in words is "twenty-one million, five hundred two thousand, twenty-five".