21021070 has 16 divisors (see below), whose sum is σ = 43243488. Its totient is φ = 7207200.

The previous prime is 21021067. The next prime is 21021083. The reversal of 21021070 is 7012012.

21021070 is nontrivially palindromic in base 9.

It is a self number, because there is not a number n which added to its sum of digits gives 21021070.

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, 150081 + ... + 150220.

It is an arithmetic number, because the mean of its divisors is an integer number (2702718).

Almost surely, 2^21021070 is an apocalyptic number.

21021070 is an abundant number, since it is smaller than the sum of its proper divisors (22222418).

21021070 is a wasteful number, since it uses less digits than its factorization.

21021070 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300315.

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

The square root of 21021070 is about 4584.8740440714. The cubic root of 21021070 is about 275.9846574822.

Adding to 21021070 its reverse (7012012), we get a palindrome (28033082).

The spelling of 21021070 in words is "twenty-one million, twenty-one thousand, seventy".