21553425 has 48 divisors (see below), whose sum is σ = 40711680. Its totient is φ = 11171520.

The previous prime is 21553421. The next prime is 21553453. The reversal of 21553425 is 52435512.

It is a happy number.

It is not a de Polignac number, because 21553425 - 2² = 21553421 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21553421) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 24544 + ... + 25406.

It is an arithmetic number, because the mean of its divisors is an integer number (848160).

Almost surely, 2^21553425 is an apocalyptic number.

21553425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21553425 is a deficient number, since it is larger than the sum of its proper divisors (19158255).

21553425 is a wasteful number, since it uses less digits than its factorization.

21553425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 919 (or 908 counting only the distinct ones).

The product of its digits is 6000, while the sum is 27.

The square root of 21553425 is about 4642.5666392632. The cubic root of 21553425 is about 278.2950174546.

Adding to 21553425 its reverse (52435512), we get a palindrome (73988937).

The spelling of 21553425 in words is "twenty-one million, five hundred fifty-three thousand, four hundred twenty-five".