21768647 has 8 divisors (see below), whose sum is σ = 22585440. Its totient is φ = 20956320.

The previous prime is 21768641. The next prime is 21768667. The reversal of 21768647 is 74686712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21768647 - 2⁶ = 21768583 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21768641) 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, 11318 + ... + 13100.

It is an arithmetic number, because the mean of its divisors is an integer number (2823180).

Almost surely, 2^21768647 is an apocalyptic number.

21768647 is a deficient number, since it is larger than the sum of its proper divisors (816793).

21768647 is a wasteful number, since it uses less digits than its factorization.

21768647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2233.

The product of its digits is 112896, while the sum is 41.

The square root of 21768647 is about 4665.6882664833. The cubic root of 21768647 is about 279.2182573795.

The spelling of 21768647 in words is "twenty-one million, seven hundred sixty-eight thousand, six hundred forty-seven".