21210070 has 32 divisors (see below), whose sum is σ = 44463168. Its totient is φ = 7133568.

The previous prime is 21210053. The next prime is 21210089. The reversal of 21210070 is 7001212.

It is a self number, because there is not a number n which added to its sum of digits gives 21210070.

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 15 ways as a sum of consecutive naturals, for example, 852 + ... + 6568.

It is an arithmetic number, because the mean of its divisors is an integer number (1389474).

Almost surely, 2^21210070 is an apocalyptic number.

21210070 is an abundant number, since it is smaller than the sum of its proper divisors (23253098).

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

21210070 is a wasteful number, since it uses less digits than its factorization.

21210070 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5784.

The product of its (nonzero) digits is 28, while the sum is 13.

The square root of 21210070 is about 4605.4391755836. The cubic root of 21210070 is about 276.8093149966.

Adding to 21210070 its reverse (7001212), we get a palindrome (28211282).

The spelling of 21210070 in words is "twenty-one million, two hundred ten thousand, seventy".