21065768 has 8 divisors (see below), whose sum is σ = 39498330. Its totient is φ = 10532880.

The previous prime is 21065767. The next prime is 21065777. The reversal of 21065768 is 86756012.

It can be written as a sum of positive squares in only one way, i.e., 19166884 + 1898884 = 4378^2 + 1378^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21065767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1316603 + ... + 1316618.

Almost surely, 2^21065768 is an apocalyptic number.

It is an amenable number.

21065768 is a deficient number, since it is larger than the sum of its proper divisors (18432562).

21065768 is a wasteful number, since it uses less digits than its factorization.

21065768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2633227 (or 2633223 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 21065768 is about 4589.7459624689. The cubic root of 21065768 is about 276.1801316587.

The spelling of 21065768 in words is "twenty-one million, sixty-five thousand, seven hundred sixty-eight".