21206710 has 48 divisors (see below), whose sum is σ = 44914176. Its totient is φ = 7187712.

The previous prime is 21206699. The next prime is 21206747. The reversal of 21206710 is 1760212.

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 23 ways as a sum of consecutive naturals, for example, 55179 + ... + 55561.

It is an arithmetic number, because the mean of its divisors is an integer number (935712).

Almost surely, 2^21206710 is an apocalyptic number.

21206710 is an abundant number, since it is smaller than the sum of its proper divisors (23707466).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21206710 is a wasteful number, since it uses less digits than its factorization.

21206710 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 517 (or 510 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 21206710 is about 4605.0743750780. The cubic root of 21206710 is about 276.7946972794.

Adding to 21206710 its reverse (1760212), we get a palindrome (22966922).

The spelling of 21206710 in words is "twenty-one million, two hundred six thousand, seven hundred ten".