21213710 has 16 divisors (see below), whose sum is σ = 43639776. Its totient is φ = 7273248.

The previous prime is 21213707. The next prime is 21213719. The reversal of 21213710 is 1731212.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213719) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 151457 + ... + 151596.

It is an arithmetic number, because the mean of its divisors is an integer number (2727486).

Almost surely, 2^21213710 is an apocalyptic number.

21213710 is an abundant number, since it is smaller than the sum of its proper divisors (22426066).

21213710 is a wasteful number, since it uses less digits than its factorization.

21213710 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 303067.

The product of its (nonzero) digits is 84, while the sum is 17.

The square root of 21213710 is about 4605.8343435256. The cubic root of 21213710 is about 276.8251491149.

Adding to 21213710 its reverse (1731212), we get a palindrome (22944922).

The spelling of 21213710 in words is "twenty-one million, two hundred thirteen thousand, seven hundred ten".