77331421 has 2 divisors, whose sum is σ = 77331422. Its totient is φ = 77331420.

The previous prime is 77331389. The next prime is 77331427. The reversal of 77331421 is 12413377.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70644025 + 6687396 = 8405^2 + 2586^2 .

It is an emirp because it is prime and its reverse (12413377) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77331421 - 2⁵ = 77331389 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 77331421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77331427) 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, 38665710 + 38665711.

It is an arithmetic number, because the mean of its divisors is an integer number (38665711).

Almost surely, 2^77331421 is an apocalyptic number.

It is an amenable number.

77331421 is a deficient number, since it is larger than the sum of its proper divisors (1).

77331421 is an equidigital number, since it uses as much as digits as its factorization.

77331421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3528, while the sum is 28.

The square root of 77331421 is about 8793.8285746312. The cubic root of 77331421 is about 426.0415900529.

Adding to 77331421 its reverse (12413377), we get a palindrome (89744798).

The spelling of 77331421 in words is "seventy-seven million, three hundred thirty-one thousand, four hundred twenty-one".