21539027 has 4 divisors (see below), whose sum is σ = 22672680. Its totient is φ = 20405376.

The previous prime is 21539009. The next prime is 21539029. The reversal of 21539027 is 72093512.

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

It is a cyclic number.

It is not a de Polignac number, because 21539027 - 2¹⁰ = 21538003 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21539029) 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, 566798 + ... + 566835.

It is an arithmetic number, because the mean of its divisors is an integer number (5668170).

Almost surely, 2^21539027 is an apocalyptic number.

21539027 is a deficient number, since it is larger than the sum of its proper divisors (1133653).

21539027 is a wasteful number, since it uses less digits than its factorization.

21539027 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1133652.

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 21539027 is about 4641.0157293420. The cubic root of 21539027 is about 278.2330352837.

The spelling of 21539027 in words is "twenty-one million, five hundred thirty-nine thousand, twenty-seven".