21368566 has 4 divisors (see below), whose sum is σ = 32052852. Its totient is φ = 10684282.

The previous prime is 21368539. The next prime is 21368569. The reversal of 21368566 is 66586312.

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

It is a super-2 number, since 2×21368566² = 913231225792712, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21368569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5342140 + ... + 5342143.

It is an arithmetic number, because the mean of its divisors is an integer number (8013213).

Almost surely, 2^21368566 is an apocalyptic number.

21368566 is a deficient number, since it is larger than the sum of its proper divisors (10684286).

21368566 is a wasteful number, since it uses less digits than its factorization.

21368566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10684285.

The product of its digits is 51840, while the sum is 37.

The square root of 21368566 is about 4622.6146281082. The cubic root of 21368566 is about 277.4971068064.

The spelling of 21368566 in words is "twenty-one million, three hundred sixty-eight thousand, five hundred sixty-six".