21013425 has 42 divisors (see below), whose sum is σ = 39100982. Its totient is φ = 11197440.

The previous prime is 21013423. The next prime is 21013427. The reversal of 21013425 is 52431012.

It is an interprime number because it is at equal distance from previous prime (21013423) and next prime (21013427).

It can be written as a sum of positive squares in 3 ways, for example, as 3272481 + 17740944 = 1809^2 + 4212^2 .

It is not a de Polignac number, because 21013425 - 2¹ = 21013423 is a prime.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21013398 and 21013407.

It is not an unprimeable number, because it can be changed into a prime (21013423) by changing a digit.

It is a polite number, since it can be written in 41 ways as a sum of consecutive naturals, for example, 17649 + ... + 18801.

Almost surely, 2^21013425 is an apocalyptic number.

21013425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21013425 is a deficient number, since it is larger than the sum of its proper divisors (18087557).

21013425 is an equidigital number, since it uses as much as digits as its factorization.

21013425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1181 (or 1161 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21013425 is about 4584.0402485144. The cubic root of 21013425 is about 275.9511964748.

Adding to 21013425 its reverse (52431012), we get a palindrome (73444437).

The spelling of 21013425 in words is "twenty-one million, thirteen thousand, four hundred twenty-five".