21727471 has 4 divisors (see below), whose sum is σ = 21737944. Its totient is φ = 21717000.

The previous prime is 21727463. The next prime is 21727477. The reversal of 21727471 is 17472712.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21727471 - 2³ = 21727463 is a prime.

It is a super-3 number, since 3×21727471³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21727477) 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, 960 + ... + 6661.

It is an arithmetic number, because the mean of its divisors is an integer number (5434486).

Almost surely, 2^21727471 is an apocalyptic number.

21727471 is a deficient number, since it is larger than the sum of its proper divisors (10473).

21727471 is an equidigital number, since it uses as much as digits as its factorization.

21727471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10472.

The product of its digits is 5488, while the sum is 31.

The square root of 21727471 is about 4661.2735384227. The cubic root of 21727471 is about 279.0420965672.

The spelling of 21727471 in words is "twenty-one million, seven hundred twenty-seven thousand, four hundred seventy-one".