21645529 has 4 divisors (see below), whose sum is σ = 21757876. Its totient is φ = 21533184.

The previous prime is 21645527. The next prime is 21645551. The reversal of 21645529 is 92554612.

It is a happy number.

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 9290304 + 12355225 = 3048^2 + 3515^2 .

It is a cyclic number.

It is not a de Polignac number, because 21645529 - 2¹ = 21645527 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21645494 and 21645503.

It is not an unprimeable number, because it can be changed into a prime (21645527) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 55884 + ... + 56269.

It is an arithmetic number, because the mean of its divisors is an integer number (5439469).

Almost surely, 2^21645529 is an apocalyptic number.

It is an amenable number.

21645529 is a deficient number, since it is larger than the sum of its proper divisors (112347).

21645529 is a wasteful number, since it uses less digits than its factorization.

21645529 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112346.

The product of its digits is 21600, while the sum is 34.

The square root of 21645529 is about 4652.4755775823. The cubic root of 21645529 is about 278.6908657498.

The spelling of 21645529 in words is "twenty-one million, six hundred forty-five thousand, five hundred twenty-nine".