21605127 has 4 divisors (see below), whose sum is σ = 28806840. Its totient is φ = 14403416.

The previous prime is 21605123. The next prime is 21605159. The reversal of 21605127 is 72150612.

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 21605127 - 2² = 21605123 is a prime.

It is a super-2 number, since 2×21605127² = 933563025372258, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21605097 and 21605106.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21605123) 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, 3600852 + ... + 3600857.

It is an arithmetic number, because the mean of its divisors is an integer number (7201710).

Almost surely, 2^21605127 is an apocalyptic number.

21605127 is a deficient number, since it is larger than the sum of its proper divisors (7201713).

21605127 is an equidigital number, since it uses as much as digits as its factorization.

21605127 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7201712.

The product of its (nonzero) digits is 840, while the sum is 24.

The square root of 21605127 is about 4648.1315601003. The cubic root of 21605127 is about 278.5173629273.

Adding to 21605127 its reverse (72150612), we get a palindrome (93755739).

The spelling of 21605127 in words is "twenty-one million, six hundred five thousand, one hundred twenty-seven".