21729364 has 12 divisors (see below), whose sum is σ = 38744244. Its totient is φ = 10659584.

The previous prime is 21729361. The next prime is 21729377. The reversal of 21729364 is 46392712.

It can be written as a sum of positive squares in 2 ways, for example, as 16402500 + 5326864 = 4050^2 + 2308^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21729361) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51037 + ... + 51460.

It is an arithmetic number, because the mean of its divisors is an integer number (3228687).

Almost surely, 2^21729364 is an apocalyptic number.

It is an amenable number.

21729364 is a deficient number, since it is larger than the sum of its proper divisors (17014880).

21729364 is a wasteful number, since it uses less digits than its factorization.

21729364 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102554 (or 102552 counting only the distinct ones).

The product of its digits is 18144, while the sum is 34.

The square root of 21729364 is about 4661.4765900946. The cubic root of 21729364 is about 279.0502001541.

The spelling of 21729364 in words is "twenty-one million, seven hundred twenty-nine thousand, three hundred sixty-four".