21717293 has 4 divisors (see below), whose sum is σ = 23387868. Its totient is φ = 20046720.

The previous prime is 21717287. The next prime is 21717307. The reversal of 21717293 is 39271712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9972964 + 11744329 = 3158^2 + 3427^2 .

It is a cyclic number.

It is not a de Polignac number, because 21717293 - 2⁴ = 21717277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21717203) 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, 835268 + ... + 835293.

It is an arithmetic number, because the mean of its divisors is an integer number (5846967).

Almost surely, 2^21717293 is an apocalyptic number.

It is an amenable number.

21717293 is a deficient number, since it is larger than the sum of its proper divisors (1670575).

21717293 is a wasteful number, since it uses less digits than its factorization.

21717293 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1670574.

The product of its digits is 5292, while the sum is 32.

The square root of 21717293 is about 4660.1816488201. The cubic root of 21717293 is about 278.9985183394.

The spelling of 21717293 in words is "twenty-one million, seven hundred seventeen thousand, two hundred ninety-three".