21689147 has 8 divisors (see below), whose sum is σ = 22022880. Its totient is φ = 21358080.

The previous prime is 21689131. The next prime is 21689149. The reversal of 21689147 is 74198612.

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

It is a cyclic number.

It is not a de Polignac number, because 21689147 - 2⁴ = 21689131 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21689147.

It is not an unprimeable number, because it can be changed into a prime (21689149) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20522 + ... + 21552.

It is an arithmetic number, because the mean of its divisors is an integer number (2752860).

Almost surely, 2^21689147 is an apocalyptic number.

21689147 is a deficient number, since it is larger than the sum of its proper divisors (333733).

21689147 is a wasteful number, since it uses less digits than its factorization.

21689147 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1333.

The product of its digits is 24192, while the sum is 38.

The square root of 21689147 is about 4657.1608303772. The cubic root of 21689147 is about 278.8779372100.

The spelling of 21689147 in words is "twenty-one million, six hundred eighty-nine thousand, one hundred forty-seven".