21427547 has 4 divisors (see below), whose sum is σ = 21624240. Its totient is φ = 21230856.

The previous prime is 21427537. The next prime is 21427583. The reversal of 21427547 is 74572412.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21427547 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21427507) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 98183 + ... + 98400.

It is an arithmetic number, because the mean of its divisors is an integer number (5406060).

Almost surely, 2^21427547 is an apocalyptic number.

21427547 is a deficient number, since it is larger than the sum of its proper divisors (196693).

21427547 is a wasteful number, since it uses less digits than its factorization.

21427547 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196692.

The product of its digits is 15680, while the sum is 32.

The square root of 21427547 is about 4628.9898466080. The cubic root of 21427547 is about 277.7521858675.

Adding to 21427547 its reverse (74572412), we get a palindrome (95999959).

The spelling of 21427547 in words is "twenty-one million, four hundred twenty-seven thousand, five hundred forty-seven".