21227081 has 2 divisors, whose sum is σ = 21227082. Its totient is φ = 21227080.

The previous prime is 21227023. The next prime is 21227099. The reversal of 21227081 is 18072212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21160000 + 67081 = 4600^2 + 259^2 .

It is a cyclic number.

It is not a de Polignac number, because 21227081 - 2¹⁴ = 21210697 is a prime.

It is a super-2 number, since 2×21227081² = 901177935561122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21227581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10613540 + 10613541.

It is an arithmetic number, because the mean of its divisors is an integer number (10613541).

Almost surely, 2^21227081 is an apocalyptic number.

It is an amenable number.

21227081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21227081 is an equidigital number, since it uses as much as digits as its factorization.

21227081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 21227081 is about 4607.2856434130. The cubic root of 21227081 is about 276.8832978573.

Adding to 21227081 its reverse (18072212), we get a palindrome (39299293).

The spelling of 21227081 in words is "twenty-one million, two hundred twenty-seven thousand, eighty-one".