21366543 has 16 divisors (see below), whose sum is σ = 31341312. Its totient is φ = 12947000.

The previous prime is 21366539. The next prime is 21366547. The reversal of 21366543 is 34566312.

It is an interprime number because it is at equal distance from previous prime (21366539) and next prime (21366547).

It is not a de Polignac number, because 21366543 - 2² = 21366539 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21366543.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21366547) 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 15 ways as a sum of consecutive naturals, for example, 1318 + ... + 6668.

It is an arithmetic number, because the mean of its divisors is an integer number (1958832).

Almost surely, 2^21366543 is an apocalyptic number.

21366543 is a deficient number, since it is larger than the sum of its proper divisors (9974769).

21366543 is an equidigital number, since it uses as much as digits as its factorization.

21366543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5387 (or 5365 counting only the distinct ones).

The product of its digits is 12960, while the sum is 30.

The square root of 21366543 is about 4622.3958073709. The cubic root of 21366543 is about 277.4883494825.

The spelling of 21366543 in words is "twenty-one million, three hundred sixty-six thousand, five hundred forty-three".