21723449 has 8 divisors (see below), whose sum is σ = 23768640. Its totient is φ = 19690000.

The previous prime is 21723419. The next prime is 21723451. The reversal of 21723449 is 94432712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-21723449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21723409) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1199 + ... + 6699.

It is an arithmetic number, because the mean of its divisors is an integer number (2971080).

Almost surely, 2^21723449 is an apocalyptic number.

It is an amenable number.

21723449 is a deficient number, since it is larger than the sum of its proper divisors (2045191).

21723449 is a wasteful number, since it uses less digits than its factorization.

21723449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5871.

The product of its digits is 12096, while the sum is 32.

The square root of 21723449 is about 4660.8420912964. The cubic root of 21723449 is about 279.0248775580.

The spelling of 21723449 in words is "twenty-one million, seven hundred twenty-three thousand, four hundred forty-nine".