21330725 has 12 divisors (see below), whose sum is σ = 28485156. Its totient is φ = 15751680.

The previous prime is 21330679. The next prime is 21330737. The reversal of 21330725 is 52703312.

It can be written as a sum of positive squares in 6 ways, for example, as 954529 + 20376196 = 977^2 + 4514^2 .

It is not a de Polignac number, because 21330725 - 2⁸ = 21330469 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 21330725.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32492 + ... + 33141.

It is an arithmetic number, because the mean of its divisors is an integer number (2373763).

Almost surely, 2^21330725 is an apocalyptic number.

21330725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21330725 is a deficient number, since it is larger than the sum of its proper divisors (7154431).

21330725 is a wasteful number, since it uses less digits than its factorization.

21330725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65656 (or 65651 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 23.

The square root of 21330725 is about 4618.5197845197. The cubic root of 21330725 is about 277.3332060463. Note that the first 3 decimals are identical.

The spelling of 21330725 in words is "twenty-one million, three hundred thirty thousand, seven hundred twenty-five".