21768359 has 4 divisors (see below), whose sum is σ = 21859680. Its totient is φ = 21677040.

The previous prime is 21768349. The next prime is 21768361. The reversal of 21768359 is 95386712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21768359 - 2⁴ = 21768343 is a prime.

It is a super-2 number, since 2×21768359² = 947722907105762, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21768349) 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 in 3 ways as a sum of consecutive naturals, for example, 45302 + ... + 45779.

It is an arithmetic number, because the mean of its divisors is an integer number (5464920).

Almost surely, 2^21768359 is an apocalyptic number.

21768359 is a deficient number, since it is larger than the sum of its proper divisors (91321).

21768359 is an equidigital number, since it uses as much as digits as its factorization.

21768359 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91320.

The product of its digits is 90720, while the sum is 41.

The square root of 21768359 is about 4665.6574027676. The cubic root of 21768359 is about 279.2170260181.

The spelling of 21768359 in words is "twenty-one million, seven hundred sixty-eight thousand, three hundred fifty-nine".