21771121 has 2 divisors, whose sum is σ = 21771122. Its totient is φ = 21771120.

The previous prime is 21771097. The next prime is 21771151. The reversal of 21771121 is 12117712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21752896 + 18225 = 4664^2 + 135^2 .

It is a cyclic number.

It is not a de Polignac number, because 21771121 - 2⁵ = 21771089 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21771092 and 21771101.

It is not a weakly prime, because it can be changed into another prime (21771151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10885560 + 10885561.

It is an arithmetic number, because the mean of its divisors is an integer number (10885561).

Almost surely, 2^21771121 is an apocalyptic number.

It is an amenable number.

21771121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21771121 is an equidigital number, since it uses as much as digits as its factorization.

21771121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 196, while the sum is 22.

The square root of 21771121 is about 4665.9533859652. The cubic root of 21771121 is about 279.2288346683.

Adding to 21771121 its reverse (12117712), we get a palindrome (33888833).

The spelling of 21771121 in words is "twenty-one million, seven hundred seventy-one thousand, one hundred twenty-one".