245721591761 has 2 divisors, whose sum is σ = 245721591762. Its totient is φ = 245721591760.

The previous prime is 245721591749. The next prime is 245721591827. The reversal of 245721591761 is 167195127542.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 216397084225 + 29324507536 = 465185^2 + 171244^2 .

It is a cyclic number.

It is not a de Polignac number, because 245721591761 - 2⁶ = 245721591697 is a prime.

It is a super-2 number, since 2×245721591761² (a number of 24 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (245721591701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 122860795880 + 122860795881.

It is an arithmetic number, because the mean of its divisors is an integer number (122860795881).

Almost surely, 2^245721591761 is an apocalyptic number.

It is an amenable number.

245721591761 is a deficient number, since it is larger than the sum of its proper divisors (1).

245721591761 is an equidigital number, since it uses as much as digits as its factorization.

245721591761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1058400, while the sum is 50.

The spelling of 245721591761 in words is "two hundred forty-five billion, seven hundred twenty-one million, five hundred ninety-one thousand, seven hundred sixty-one".