21543769 has 4 divisors (see below), whose sum is σ = 23200996. Its totient is φ = 19886544.

The previous prime is 21543757. The next prime is 21543779. The reversal of 21543769 is 96734512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 13046544 + 8497225 = 3612^2 + 2915^2 .

It is a cyclic number.

It is not a de Polignac number, because 21543769 - 2¹¹ = 21541721 is a prime.

It is a super-2 number, since 2×21543769² = 928267965450722, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21543779) 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 in 3 ways as a sum of consecutive naturals, for example, 828594 + ... + 828619.

It is an arithmetic number, because the mean of its divisors is an integer number (5800249).

Almost surely, 2^21543769 is an apocalyptic number.

It is an amenable number.

21543769 is a deficient number, since it is larger than the sum of its proper divisors (1657227).

21543769 is a wasteful number, since it uses less digits than its factorization.

21543769 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1657226.

The product of its digits is 45360, while the sum is 37.

The square root of 21543769 is about 4641.5265807706. The cubic root of 21543769 is about 278.2534522419.

The spelling of 21543769 in words is "twenty-one million, five hundred forty-three thousand, seven hundred sixty-nine".