21730529 has 4 divisors (see below), whose sum is σ = 21889284. Its totient is φ = 21571776.

The previous prime is 21730519. The next prime is 21730531. The reversal of 21730529 is 92503712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13890529 + 7840000 = 3727^2 + 2800^2 .

It is a cyclic number.

It is not a de Polignac number, because 21730529 - 2⁸ = 21730273 is a prime.

It is a pancake number, because a pancake can be divided into 21730529 parts by 6592 straight cuts.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21730519) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 79172 + ... + 79445.

It is an arithmetic number, because the mean of its divisors is an integer number (5472321).

Almost surely, 2^21730529 is an apocalyptic number.

It is an amenable number.

21730529 is a deficient number, since it is larger than the sum of its proper divisors (158755).

21730529 is a wasteful number, since it uses less digits than its factorization.

21730529 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158754.

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 21730529 is about 4661.6015488242. The cubic root of 21730529 is about 279.0551870722.

The spelling of 21730529 in words is "twenty-one million, seven hundred thirty thousand, five hundred twenty-nine".