21705512 has 8 divisors (see below), whose sum is σ = 40697850. Its totient is φ = 10852752.

The previous prime is 21705503. The next prime is 21705517. The reversal of 21705512 is 21550712.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21659716 + 45796 = 4654^2 + 214^2 .

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

It is a super-3 number, since 3×21705512³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (21705517) 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 as a sum of consecutive naturals, namely, 1356587 + ... + 1356602.

Almost surely, 2^21705512 is an apocalyptic number.

It is an amenable number.

21705512 is a deficient number, since it is larger than the sum of its proper divisors (18992338).

21705512 is a wasteful number, since it uses less digits than its factorization.

21705512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2713195 (or 2713191 counting only the distinct ones).

The product of its (nonzero) digits is 700, while the sum is 23.

The square root of 21705512 is about 4658.9174708295. The cubic root of 21705512 is about 278.9480596861.

The spelling of 21705512 in words is "twenty-one million, seven hundred five thousand, five hundred twelve".