21153425 has 6 divisors (see below), whose sum is σ = 26230278. Its totient is φ = 16922720.

The previous prime is 21153409. The next prime is 21153427. The reversal of 21153425 is 52435112.

It can be written as a sum of positive squares in 3 ways, for example, as 295936 + 20857489 = 544^2 + 4567^2 .

It is not a de Polignac number, because 21153425 - 2⁴ = 21153409 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 21153425.

It is not an unprimeable number, because it can be changed into a prime (21153427) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 423044 + ... + 423093.

It is an arithmetic number, because the mean of its divisors is an integer number (4371713).

Almost surely, 2^21153425 is an apocalyptic number.

21153425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21153425 is a deficient number, since it is larger than the sum of its proper divisors (5076853).

21153425 is an equidigital number, since it uses as much as digits as its factorization.

21153425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 846147 (or 846142 counting only the distinct ones).

The product of its digits is 1200, while the sum is 23.

The square root of 21153425 is about 4599.2852705611. The cubic root of 21153425 is about 276.5626736143.

Adding to 21153425 its reverse (52435112), we get a palindrome (73588537).

The spelling of 21153425 in words is "twenty-one million, one hundred fifty-three thousand, four hundred twenty-five".