21689829 has 16 divisors (see below), whose sum is σ = 36723840. Its totient is φ = 12394080.

The previous prime is 21689827. The next prime is 21689867. The reversal of 21689829 is 92898612.

It is not a de Polignac number, because 21689829 - 2¹ = 21689827 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21689821) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 57192 + ... + 57569.

It is an arithmetic number, because the mean of its divisors is an integer number (2295240).

Almost surely, 2^21689829 is an apocalyptic number.

It is an amenable number.

21689829 is a deficient number, since it is larger than the sum of its proper divisors (15034011).

21689829 is a wasteful number, since it uses less digits than its factorization.

21689829 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114777 (or 114771 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The square root of 21689829 is about 4657.2340503780. The cubic root of 21689829 is about 278.8808602196.

The spelling of 21689829 in words is "twenty-one million, six hundred eighty-nine thousand, eight hundred twenty-nine".