721542245564137 has 2 divisors, whose sum is σ = 721542245564138. Its totient is φ = 721542245564136.

The previous prime is 721542245564113. The next prime is 721542245564201. The reversal of 721542245564137 is 731465542245127.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 720027920888896 + 1514324675241 = 26833336^2 + 1230579^2 .

It is an emirp because it is prime and its reverse (731465542245127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721542245564137 - 2⁷ = 721542245564009 is a prime.

It is not a weakly prime, because it can be changed into another prime (721542245564837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360771122782068 + 360771122782069.

It is an arithmetic number, because the mean of its divisors is an integer number (360771122782069).

Almost surely, 2^{721542245564137} is an apocalyptic number.

It is an amenable number.

721542245564137 is a deficient number, since it is larger than the sum of its proper divisors (1).

721542245564137 is an equidigital number, since it uses as much as digits as its factorization.

721542245564137 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56448000, while the sum is 58.

The spelling of 721542245564137 in words is "seven hundred twenty-one trillion, five hundred forty-two billion, two hundred forty-five million, five hundred sixty-four thousand, one hundred thirty-seven".