21439727 has 4 divisors (see below), whose sum is σ = 21486696. Its totient is φ = 21392760.

The previous prime is 21439723. The next prime is 21439739. The reversal of 21439727 is 72793412.

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 21439727 - 2² = 21439723 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21439721) 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, 22793 + ... + 23714.

It is an arithmetic number, because the mean of its divisors is an integer number (5371674).

Almost surely, 2^21439727 is an apocalyptic number.

21439727 is a deficient number, since it is larger than the sum of its proper divisors (46969).

21439727 is an equidigital number, since it uses as much as digits as its factorization.

21439727 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46968.

The product of its digits is 21168, while the sum is 35.

The square root of 21439727 is about 4630.3052815122. The cubic root of 21439727 is about 277.8048031958.

The spelling of 21439727 in words is "twenty-one million, four hundred thirty-nine thousand, seven hundred twenty-seven".