21540047 has 8 divisors (see below), whose sum is σ = 22317120. Its totient is φ = 20775040.

The previous prime is 21540023. The next prime is 21540049. The reversal of 21540047 is 74004512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21540047 - 2¹⁶ = 21474511 is a prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21540049) 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 7 ways as a sum of consecutive naturals, for example, 698 + ... + 6600.

It is an arithmetic number, because the mean of its divisors is an integer number (2789640).

Almost surely, 2^21540047 is an apocalyptic number.

21540047 is a deficient number, since it is larger than the sum of its proper divisors (777073).

21540047 is an equidigital number, since it uses as much as digits as its factorization.

21540047 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6033.

The product of its (nonzero) digits is 1120, while the sum is 23.

The square root of 21540047 is about 4641.1256177785. The cubic root of 21540047 is about 278.2374272063.

Adding to 21540047 its reverse (74004512), we get a palindrome (95544559).

The spelling of 21540047 in words is "twenty-one million, five hundred forty thousand, forty-seven".