21827121 has 4 divisors (see below), whose sum is σ = 29102832. Its totient is φ = 14551412.

The previous prime is 21827119. The next prime is 21827123. The reversal of 21827121 is 12172812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (21827119) and next prime (21827123).

It is a cyclic number.

It is not a de Polignac number, because 21827121 - 2¹ = 21827119 is a prime.

It is a super-2 number, since 2×21827121² = 952846422297282, which contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21827091 and 21827100.

It is not an unprimeable number, because it can be changed into a prime (21827123) 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, 3637851 + ... + 3637856.

It is an arithmetic number, because the mean of its divisors is an integer number (7275708).

Almost surely, 2^21827121 is an apocalyptic number.

It is an amenable number.

21827121 is a deficient number, since it is larger than the sum of its proper divisors (7275711).

21827121 is an equidigital number, since it uses as much as digits as its factorization.

21827121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7275710.

The product of its digits is 448, while the sum is 24.

The square root of 21827121 is about 4671.9504492235. The cubic root of 21827121 is about 279.4680418699.

Adding to 21827121 its reverse (12172812), we get a palindrome (33999933).

The spelling of 21827121 in words is "twenty-one million, eight hundred twenty-seven thousand, one hundred twenty-one".