21210205 has 8 divisors (see below), whose sum is σ = 25884000. Its totient is φ = 16680336.

The previous prime is 21210197. The next prime is 21210221. The reversal of 21210205 is 50201212.

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 21210205 - 2³ = 21210197 is a prime.

It is a super-2 number, since 2×21210205² = 899745592284050, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35655 + ... + 36244.

It is an arithmetic number, because the mean of its divisors is an integer number (3235500).

Almost surely, 2^21210205 is an apocalyptic number.

It is an amenable number.

21210205 is a deficient number, since it is larger than the sum of its proper divisors (4673795).

21210205 is an equidigital number, since it uses as much as digits as its factorization.

21210205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71963.

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 21210205 is about 4605.4538321429. The cubic root of 21210205 is about 276.8099022834.

Adding to 21210205 its reverse (50201212), we get a palindrome (71411417).

The spelling of 21210205 in words is "twenty-one million, two hundred ten thousand, two hundred five".