21821210 has 32 divisors (see below), whose sum is σ = 41513472. Its totient is φ = 8245440.

The previous prime is 21821201. The next prime is 21821221. The reversal of 21821210 is 1212812.

It is a happy number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12512 + ... + 14148.

It is an arithmetic number, because the mean of its divisors is an integer number (1297296).

Almost surely, 2^21821210 is an apocalyptic number.

21821210 is a deficient number, since it is larger than the sum of its proper divisors (19692262).

21821210 is a wasteful number, since it uses less digits than its factorization.

21821210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1718.

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 21821210 is about 4671.3178012206. The cubic root of 21821210 is about 279.4428120234.

The spelling of 21821210 in words is "twenty-one million, eight hundred twenty-one thousand, two hundred ten".