21729080 has 16 divisors (see below), whose sum is σ = 48890520. Its totient is φ = 8691616.

The previous prime is 21729079. The next prime is 21729119. The reversal of 21729080 is 8092712.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 271574 + ... + 271653.

Almost surely, 2^21729080 is an apocalyptic number.

21729080 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21729080 is an abundant number, since it is smaller than the sum of its proper divisors (27161440).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21729080 is a wasteful number, since it uses less digits than its factorization.

21729080 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 543238 (or 543234 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 21729080 is about 4661.4461275445. The cubic root of 21729080 is about 279.0489844320.

The spelling of 21729080 in words is "twenty-one million, seven hundred twenty-nine thousand, eighty".