71221021 has 2 divisors, whose sum is σ = 71221022. Its totient is φ = 71221020.

The previous prime is 71221001. The next prime is 71221049. The reversal of 71221021 is 12012217.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 70744921 + 476100 = 8411^2 + 690^2 .

It is a cyclic number.

It is not a de Polignac number, because 71221021 - 2¹³ = 71212829 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 71220986 and 71221004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71221001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35610510 + 35610511.

It is an arithmetic number, because the mean of its divisors is an integer number (35610511).

Almost surely, 2^71221021 is an apocalyptic number.

It is an amenable number.

71221021 is a deficient number, since it is larger than the sum of its proper divisors (1).

71221021 is an equidigital number, since it uses as much as digits as its factorization.

71221021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 56, while the sum is 16.

The square root of 71221021 is about 8439.2547656769. The cubic root of 71221021 is about 414.5110048234.

Adding to 71221021 its reverse (12012217), we get a palindrome (83233238).

The spelling of 71221021 in words is "seventy-one million, two hundred twenty-one thousand, twenty-one".