21609242 has 8 divisors (see below), whose sum is σ = 32897856. Its totient is φ = 10643292.

The previous prime is 21609239. The next prime is 21609277. The reversal of 21609242 is 24290612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 80498 + ... + 80765.

It is an arithmetic number, because the mean of its divisors is an integer number (4112232).

Almost surely, 2^21609242 is an apocalyptic number.

21609242 is a deficient number, since it is larger than the sum of its proper divisors (11288614).

21609242 is a wasteful number, since it uses less digits than its factorization.

21609242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161332.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 21609242 is about 4648.5741900071. The cubic root of 21609242 is about 278.5350443198.

Adding to 21609242 its reverse (24290612), we get a palindrome (45899854).

The spelling of 21609242 in words is "twenty-one million, six hundred nine thousand, two hundred forty-two".