21320025 has 12 divisors (see below), whose sum is σ = 35249232. Its totient is φ = 11370640.

The previous prime is 21320021. The next prime is 21320051. The reversal of 21320025 is 52002312.

It is not a de Polignac number, because 21320025 - 2² = 21320021 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21319986 and 21320013.

It is not an unprimeable number, because it can be changed into a prime (21320021) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 142059 + ... + 142208.

It is an arithmetic number, because the mean of its divisors is an integer number (2937436).

Almost surely, 2^21320025 is an apocalyptic number.

21320025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21320025 is a deficient number, since it is larger than the sum of its proper divisors (13929207).

21320025 is a wasteful number, since it uses less digits than its factorization.

21320025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284280 (or 284275 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 15.

The square root of 21320025 is about 4617.3612594208. The cubic root of 21320025 is about 277.2868259752.

Adding to 21320025 its reverse (52002312), we get a palindrome (73322337).

The spelling of 21320025 in words is "twenty-one million, three hundred twenty thousand, twenty-five".