21829609 has 4 divisors (see below), whose sum is σ = 21859204. Its totient is φ = 21800016.

The previous prime is 21829607. The next prime is 21829627. The reversal of 21829609 is 90692812.

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 13690000 + 8139609 = 3700^2 + 2853^2 .

It is a cyclic number.

It is not a de Polignac number, because 21829609 - 2¹ = 21829607 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21829607) 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, 13662 + ... + 15175.

It is an arithmetic number, because the mean of its divisors is an integer number (5464801).

Almost surely, 2^21829609 is an apocalyptic number.

It is an amenable number.

21829609 is a deficient number, since it is larger than the sum of its proper divisors (29595).

21829609 is an equidigital number, since it uses as much as digits as its factorization.

21829609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29594.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 21829609 is about 4672.2167115835. The cubic root of 21829609 is about 279.4786600067.

The spelling of 21829609 in words is "twenty-one million, eight hundred twenty-nine thousand, six hundred nine".