21210425 has 6 divisors (see below), whose sum is σ = 26300958. Its totient is φ = 16968320.

The previous prime is 21210389. The next prime is 21210433. The reversal of 21210425 is 52401212.

It can be written as a sum of positive squares in 3 ways, for example, as 4791721 + 16418704 = 2189^2 + 4052^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21210425 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 424184 + ... + 424233.

It is an arithmetic number, because the mean of its divisors is an integer number (4383493).

Almost surely, 2^21210425 is an apocalyptic number.

21210425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21210425 is a deficient number, since it is larger than the sum of its proper divisors (5090533).

21210425 is an equidigital number, since it uses as much as digits as its factorization.

21210425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 848427 (or 848422 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21210425 is about 4605.4777168064. The cubic root of 21210425 is about 276.8108593379.

Adding to 21210425 its reverse (52401212), we get a palindrome (73611637).

The spelling of 21210425 in words is "twenty-one million, two hundred ten thousand, four hundred twenty-five".