21729759 has 16 divisors (see below), whose sum is σ = 29635200. Its totient is φ = 14158496.

The previous prime is 21729751. The next prime is 21729781. The reversal of 21729759 is 95792712.

It is a cyclic number.

It is not a de Polignac number, because 21729759 - 2³ = 21729751 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21729759.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21729751) 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, 51652 + ... + 52070.

It is an arithmetic number, because the mean of its divisors is an integer number (1852200).

Almost surely, 2^21729759 is an apocalyptic number.

21729759 is a deficient number, since it is larger than the sum of its proper divisors (7905441).

21729759 is a wasteful number, since it uses less digits than its factorization.

21729759 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 774.

The product of its digits is 79380, while the sum is 42.

The square root of 21729759 is about 4661.5189584512. The cubic root of 21729759 is about 279.0518910175.

The spelling of 21729759 in words is "twenty-one million, seven hundred twenty-nine thousand, seven hundred fifty-nine".