21006712 has 8 divisors (see below), whose sum is σ = 39387600. Its totient is φ = 10503352.

The previous prime is 21006707. The next prime is 21006731. The reversal of 21006712 is 21760012.

It is a tau number, because it is divible by the number of its divisors (8).

It is a self number, because there is not a number n which added to its sum of digits gives 21006712.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1312912 + ... + 1312927.

It is an arithmetic number, because the mean of its divisors is an integer number (4923450).

Almost surely, 2^21006712 is an apocalyptic number.

It is an amenable number.

21006712 is a deficient number, since it is larger than the sum of its proper divisors (18380888).

21006712 is a wasteful number, since it uses less digits than its factorization.

21006712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2625845 (or 2625841 counting only the distinct ones).

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

The square root of 21006712 is about 4583.3079756874. The cubic root of 21006712 is about 275.9218079977.

Adding to 21006712 its reverse (21760012), we get a palindrome (42766724).

The spelling of 21006712 in words is "twenty-one million, six thousand, seven hundred twelve".