77121553321 has 2 divisors, whose sum is σ = 77121553322. Its totient is φ = 77121553320.

The previous prime is 77121553309. The next prime is 77121553343. The reversal of 77121553321 is 12335512177.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62640078400 + 14481474921 = 250280^2 + 120339^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77121553321 is a prime.

It is a super-2 number, since 2×77121553321² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (77121553351) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38560776660 + 38560776661.

It is an arithmetic number, because the mean of its divisors is an integer number (38560776661).

Almost surely, 2^77121553321 is an apocalyptic number.

It is an amenable number.

77121553321 is a deficient number, since it is larger than the sum of its proper divisors (1).

77121553321 is an equidigital number, since it uses as much as digits as its factorization.

77121553321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 44100, while the sum is 37.

The spelling of 77121553321 in words is "seventy-seven billion, one hundred twenty-one million, five hundred fifty-three thousand, three hundred twenty-one".