21073529 has 4 divisors (see below), whose sum is σ = 21082740. Its totient is φ = 21064320.

The previous prime is 21073519. The next prime is 21073553. The reversal of 21073529 is 92537012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 14077504 + 6996025 = 3752^2 + 2645^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21073529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21073519) 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, 1757 + ... + 6725.

It is an arithmetic number, because the mean of its divisors is an integer number (5270685).

Almost surely, 2^21073529 is an apocalyptic number.

It is an amenable number.

21073529 is a deficient number, since it is larger than the sum of its proper divisors (9211).

21073529 is an equidigital number, since it uses as much as digits as its factorization.

21073529 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9210.

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

The square root of 21073529 is about 4590.5913562416. The cubic root of 21073529 is about 276.2140440362.

The spelling of 21073529 in words is "twenty-one million, seventy-three thousand, five hundred twenty-nine".