7261211981 has 2 divisors, whose sum is σ = 7261211982. Its totient is φ = 7261211980.

The previous prime is 7261211977. The next prime is 7261212037. The reversal of 7261211981 is 1891121627.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6001600900 + 1259611081 = 77470^2 + 35491^2 .

It is an emirp because it is prime and its reverse (1891121627) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 7261211981 - 2² = 7261211977 is a prime.

It is a super-2 number, since 2×7261211981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7261211911) 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, 3630605990 + 3630605991.

It is an arithmetic number, because the mean of its divisors is an integer number (3630605991).

Almost surely, 2^7261211981 is an apocalyptic number.

It is an amenable number.

7261211981 is a deficient number, since it is larger than the sum of its proper divisors (1).

7261211981 is an equidigital number, since it uses as much as digits as its factorization.

7261211981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12096, while the sum is 38.

The square root of 7261211981 is about 85212.7454140518. The cubic root of 7261211981 is about 1936.4355120848.

The spelling of 7261211981 in words is "seven billion, two hundred sixty-one million, two hundred eleven thousand, nine hundred eighty-one".