77750221 has 2 divisors, whose sum is σ = 77750222. Its totient is φ = 77750220.

The previous prime is 77750213. The next prime is 77750251. The reversal of 77750221 is 12205777.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 53494596 + 24255625 = 7314^2 + 4925^2 .

It is an emirp because it is prime and its reverse (12205777) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77750221 - 2³ = 77750213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77750251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38875110 + 38875111.

It is an arithmetic number, because the mean of its divisors is an integer number (38875111).

Almost surely, 2^77750221 is an apocalyptic number.

It is an amenable number.

77750221 is a deficient number, since it is larger than the sum of its proper divisors (1).

77750221 is an equidigital number, since it uses as much as digits as its factorization.

77750221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6860, while the sum is 31.

The square root of 77750221 is about 8817.6085760256. The cubic root of 77750221 is about 426.8093033712.

Adding to 77750221 its reverse (12205777), we get a palindrome (89955998).

The spelling of 77750221 in words is "seventy-seven million, seven hundred fifty thousand, two hundred twenty-one".