21609147 has 48 divisors (see below), whose sum is σ = 35868960. Its totient is φ = 11515392.

The previous prime is 21609131. The next prime is 21609149. The reversal of 21609147 is 74190612.

It is a happy number.

It is not a de Polignac number, because 21609147 - 2⁴ = 21609131 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21609149) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 157663 + ... + 157799.

It is an arithmetic number, because the mean of its divisors is an integer number (747270).

Almost surely, 2^21609147 is an apocalyptic number.

21609147 is a deficient number, since it is larger than the sum of its proper divisors (14259813).

21609147 is a wasteful number, since it uses less digits than its factorization.

21609147 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220 (or 213 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 21609147 is about 4648.5639718089. The cubic root of 21609147 is about 278.5346361477.

Adding to 21609147 its reverse (74190612), we get a palindrome (95799759).

It can be divided in two parts, 21609 and 147, that multiplied together give a cube (3176523 = 147³).

The spelling of 21609147 in words is "twenty-one million, six hundred nine thousand, one hundred forty-seven".