21356727 has 16 divisors (see below), whose sum is σ = 32613120. Its totient is φ = 12177792.

The previous prime is 21356723. The next prime is 21356759. The reversal of 21356727 is 72765312.

It is not a de Polignac number, because 21356727 - 2² = 21356723 is a prime.

It is a super-2 number, since 2×21356727² = 912219576305058, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21356723) 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 15 ways as a sum of consecutive naturals, for example, 13599 + ... + 15087.

It is an arithmetic number, because the mean of its divisors is an integer number (2038320).

Almost surely, 2^21356727 is an apocalyptic number.

21356727 is a deficient number, since it is larger than the sum of its proper divisors (11256393).

21356727 is a wasteful number, since it uses less digits than its factorization.

21356727 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2182.

The product of its digits is 17640, while the sum is 33.

The square root of 21356727 is about 4621.3338983458. Note that the first 3 decimals coincide. The cubic root of 21356727 is about 277.4458493478.

The spelling of 21356727 in words is "twenty-one million, three hundred fifty-six thousand, seven hundred twenty-seven".