21517293 has 8 divisors (see below), whose sum is σ = 32788288. Its totient is φ = 12295584.

The previous prime is 21517289. The next prime is 21517303. The reversal of 21517293 is 39271512.

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

It is not a de Polignac number, because 21517293 - 2² = 21517289 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21517293.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21517283) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 512296 + ... + 512337.

It is an arithmetic number, because the mean of its divisors is an integer number (4098536).

Almost surely, 2^21517293 is an apocalyptic number.

It is an amenable number.

21517293 is a deficient number, since it is larger than the sum of its proper divisors (11270995).

21517293 is a wasteful number, since it uses less digits than its factorization.

21517293 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1024643.

The product of its digits is 3780, while the sum is 30.

The square root of 21517293 is about 4638.6736250786. The cubic root of 21517293 is about 278.1394199147.

The spelling of 21517293 in words is "twenty-one million, five hundred seventeen thousand, two hundred ninety-three".