21381425 has 12 divisors (see below), whose sum is σ = 28552860. Its totient is φ = 15789120.

The previous prime is 21381407. The next prime is 21381433. The reversal of 21381425 is 52418312.

It can be written as a sum of positive squares in 6 ways, for example, as 1658944 + 19722481 = 1288^2 + 4441^2 .

It is not a de Polignac number, because 21381425 - 2⁶ = 21381361 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21381394 and 21381403.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32570 + ... + 33219.

It is an arithmetic number, because the mean of its divisors is an integer number (2379405).

Almost surely, 2^21381425 is an apocalyptic number.

21381425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21381425 is a deficient number, since it is larger than the sum of its proper divisors (7171435).

21381425 is a wasteful number, since it uses less digits than its factorization.

21381425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65812 (or 65807 counting only the distinct ones).

The product of its digits is 1920, while the sum is 26.

The square root of 21381425 is about 4624.0052984399. The cubic root of 21381425 is about 277.5527589539.

Adding to 21381425 its reverse (52418312), we get a palindrome (73799737).

The spelling of 21381425 in words is "twenty-one million, three hundred eighty-one thousand, four hundred twenty-five".