77731321 has 2 divisors, whose sum is σ = 77731322. Its totient is φ = 77731320.

The previous prime is 77731309. The next prime is 77731343. The reversal of 77731321 is 12313777.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73874025 + 3857296 = 8595^2 + 1964^2 .

It is a cyclic number.

It is not a de Polignac number, because 77731321 - 2⁷ = 77731193 is a prime.

It is not a weakly prime, because it can be changed into another prime (77731301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38865660 + 38865661.

It is an arithmetic number, because the mean of its divisors is an integer number (38865661).

Almost surely, 2^77731321 is an apocalyptic number.

It is an amenable number.

77731321 is a deficient number, since it is larger than the sum of its proper divisors (1).

77731321 is an equidigital number, since it uses as much as digits as its factorization.

77731321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6174, while the sum is 31.

The square root of 77731321 is about 8816.5367917340. The cubic root of 77731321 is about 426.7747167619.

The spelling of 77731321 in words is "seventy-seven million, seven hundred thirty-one thousand, three hundred twenty-one".