21736481 has 4 divisors (see below), whose sum is σ = 23408532. Its totient is φ = 20064432.

The previous prime is 21736469. The next prime is 21736483. The reversal of 21736481 is 18463712.

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 5664400 + 16072081 = 2380^2 + 4009^2 .

It is a cyclic number.

It is not a de Polignac number, because 21736481 - 2⁶ = 21736417 is a prime.

It is a super-2 number, since 2×21736481² = 944949212526722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21736483) 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, 836006 + ... + 836031.

It is an arithmetic number, because the mean of its divisors is an integer number (5852133).

Almost surely, 2^21736481 is an apocalyptic number.

It is an amenable number.

21736481 is a deficient number, since it is larger than the sum of its proper divisors (1672051).

21736481 is a wasteful number, since it uses less digits than its factorization.

21736481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1672050.

The product of its digits is 8064, while the sum is 32.

The square root of 21736481 is about 4662.2399123168. The cubic root of 21736481 is about 279.0806625197.

The spelling of 21736481 in words is "twenty-one million, seven hundred thirty-six thousand, four hundred eighty-one".