21243697 has 8 divisors (see below), whose sum is σ = 22481280. Its totient is φ = 20032320.

The previous prime is 21243683. The next prime is 21243707. The reversal of 21243697 is 79634212.

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

It is a cyclic number.

It is not a de Polignac number, because 21243697 - 2¹⁵ = 21210929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21243637) 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, 4872 + ... + 8137.

It is an arithmetic number, because the mean of its divisors is an integer number (2810160).

Almost surely, 2^21243697 is an apocalyptic number.

It is an amenable number.

21243697 is a deficient number, since it is larger than the sum of its proper divisors (1237583).

21243697 is a wasteful number, since it uses less digits than its factorization.

21243697 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13103.

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

The square root of 21243697 is about 4609.0885216060. The cubic root of 21243697 is about 276.9555246661.

The spelling of 21243697 in words is "twenty-one million, two hundred forty-three thousand, six hundred ninety-seven".