21730725 has 18 divisors (see below), whose sum is σ = 38922546. Its totient is φ = 11589600.

The previous prime is 21730693. The next prime is 21730727. The reversal of 21730725 is 52703712.

It can be written as a sum of positive squares in 3 ways, for example, as 191844 + 21538881 = 438^2 + 4641^2 .

It is not a de Polignac number, because 21730725 - 2⁵ = 21730693 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21730727) by changing a digit.

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 17 ways as a sum of consecutive naturals, for example, 48066 + ... + 48515.

Almost surely, 2^21730725 is an apocalyptic number.

21730725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21730725 is a deficient number, since it is larger than the sum of its proper divisors (17191821).

21730725 is a wasteful number, since it uses less digits than its factorization.

21730725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96597 (or 96589 counting only the distinct ones).

The product of its (nonzero) digits is 2940, while the sum is 27.

The square root of 21730725 is about 4661.6225715946. The cubic root of 21730725 is about 279.0560260555.

The spelling of 21730725 in words is "twenty-one million, seven hundred thirty thousand, seven hundred twenty-five".