21712205 has 8 divisors (see below), whose sum is σ = 26660832. Its totient is φ = 16965648.

The previous prime is 21712169. The next prime is 21712211. The reversal of 21712205 is 50221712.

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 21712205 - 2¹⁸ = 21450061 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 50279 + ... + 50708.

It is an arithmetic number, because the mean of its divisors is an integer number (3332604).

Almost surely, 2^21712205 is an apocalyptic number.

It is an amenable number.

21712205 is a deficient number, since it is larger than the sum of its proper divisors (4948627).

21712205 is a wasteful number, since it uses less digits than its factorization.

21712205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101035.

The product of its (nonzero) digits is 280, while the sum is 20.

The square root of 21712205 is about 4659.6357153752. The cubic root of 21712205 is about 278.9767284024.

Adding to 21712205 its reverse (50221712), we get a palindrome (71933917).

The spelling of 21712205 in words is "twenty-one million, seven hundred twelve thousand, two hundred five".