21745329 has 16 divisors (see below), whose sum is σ = 32316480. Its totient is φ = 12925440.

The previous prime is 21745309. The next prime is 21745337. The reversal of 21745329 is 92354712.

It is not a de Polignac number, because 21745329 - 2⁷ = 21745201 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21745329.

It is not an unprimeable number, because it can be changed into a prime (21745309) 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, 10252 + ... + 12189.

It is an arithmetic number, because the mean of its divisors is an integer number (2019780).

Almost surely, 2^21745329 is an apocalyptic number.

It is an amenable number.

21745329 is a deficient number, since it is larger than the sum of its proper divisors (10571151).

21745329 is a wasteful number, since it uses less digits than its factorization.

21745329 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22480.

The product of its digits is 15120, while the sum is 33.

The square root of 21745329 is about 4663.1887158896. The cubic root of 21745329 is about 279.1185246853.

It can be divided in two parts, 2174 and 5329, that added together give a triangular number (7503 = T₁₂₂).

The spelling of 21745329 in words is "twenty-one million, seven hundred forty-five thousand, three hundred twenty-nine".