21297225 has 24 divisors (see below), whose sum is σ = 35345952. Its totient is φ = 11315200.

The previous prime is 21297203. The next prime is 21297247. The reversal of 21297225 is 52279212.

It is an interprime number because it is at equal distance from previous prime (21297203) and next prime (21297247).

It is not a de Polignac number, because 21297225 - 2⁵ = 21297193 is a prime.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21297192 and 21297201.

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 23 ways as a sum of consecutive naturals, for example, 32905 + ... + 33545.

It is an arithmetic number, because the mean of its divisors is an integer number (1472748).

Almost surely, 2^21297225 is an apocalyptic number.

21297225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21297225 is a deficient number, since it is larger than the sum of its proper divisors (14048727).

21297225 is a wasteful number, since it uses less digits than its factorization.

21297225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1097 (or 1092 counting only the distinct ones).

The product of its digits is 5040, while the sum is 30.

The square root of 21297225 is about 4614.8916563664. The cubic root of 21297225 is about 277.1879456246.

The spelling of 21297225 in words is "twenty-one million, two hundred ninety-seven thousand, two hundred twenty-five".