21729304 has 8 divisors (see below), whose sum is σ = 40742460. Its totient is φ = 10864648.

The previous prime is 21729289. The next prime is 21729307. The reversal of 21729304 is 40392712.

It is a tau number, because it is divible by the number of its divisors (8).

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21729307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1358074 + ... + 1358089.

Almost surely, 2^21729304 is an apocalyptic number.

It is an amenable number.

21729304 is a deficient number, since it is larger than the sum of its proper divisors (19013156).

21729304 is a wasteful number, since it uses less digits than its factorization.

21729304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2716169 (or 2716165 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 21729304 is about 4661.4701543612. The cubic root of 21729304 is about 279.0499433123.

It can be divided in two parts, 2172 and 9304, that added together give a triangular number (11476 = T₁₅₁).

The spelling of 21729304 in words is "twenty-one million, seven hundred twenty-nine thousand, three hundred four".