21791768 has 32 divisors (see below), whose sum is σ = 41979600. Its totient is φ = 10601472.

The previous prime is 21791761. The next prime is 21791797. The reversal of 21791768 is 86719712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21791761) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64496 + ... + 64832.

Almost surely, 2^21791768 is an apocalyptic number.

It is an amenable number.

21791768 is a deficient number, since it is larger than the sum of its proper divisors (20187832).

21791768 is a wasteful number, since it uses less digits than its factorization.

21791768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 539 (or 535 counting only the distinct ones).

The product of its digits is 42336, while the sum is 41.

The square root of 21791768 is about 4668.1653783901. The cubic root of 21791768 is about 279.3170771952.

The spelling of 21791768 in words is "twenty-one million, seven hundred ninety-one thousand, seven hundred sixty-eight".