21261425 has 6 divisors (see below), whose sum is σ = 26364198. Its totient is φ = 17009120.

The previous prime is 21261413. The next prime is 21261433. The reversal of 21261425 is 52416212.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 758641 + 20502784 = 871^2 + 4528^2 .

It is not a de Polignac number, because 21261425 - 2²² = 17067121 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21261425.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 425204 + ... + 425253.

It is an arithmetic number, because the mean of its divisors is an integer number (4394033).

Almost surely, 2^21261425 is an apocalyptic number.

21261425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21261425 is a deficient number, since it is larger than the sum of its proper divisors (5102773).

21261425 is an equidigital number, since it uses as much as digits as its factorization.

21261425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 850467 (or 850462 counting only the distinct ones).

The product of its digits is 960, while the sum is 23.

The square root of 21261425 is about 4611.0112773664. The cubic root of 21261425 is about 277.0325436270.

Adding to 21261425 its reverse (52416212), we get a palindrome (73677637).

The spelling of 21261425 in words is "twenty-one million, two hundred sixty-one thousand, four hundred twenty-five".