77230721 has 4 divisors (see below), whose sum is σ = 78027012. Its totient is φ = 76434432.

The previous prime is 77230717. The next prime is 77230759. The reversal of 77230721 is 12703277.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 62980096 + 14250625 = 7936^2 + 3775^2 .

It is a cyclic number.

It is not a de Polignac number, because 77230721 - 2² = 77230717 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (77230771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 398000 + ... + 398193.

It is an arithmetic number, because the mean of its divisors is an integer number (19506753).

Almost surely, 2^77230721 is an apocalyptic number.

It is an amenable number.

77230721 is a deficient number, since it is larger than the sum of its proper divisors (796291).

77230721 is an equidigital number, since it uses as much as digits as its factorization.

77230721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 796290.

The product of its (nonzero) digits is 4116, while the sum is 29.

The square root of 77230721 is about 8788.1011031963. The cubic root of 77230721 is about 425.8565810645.

Adding to 77230721 its reverse (12703277), we get a palindrome (89933998).

The spelling of 77230721 in words is "seventy-seven million, two hundred thirty thousand, seven hundred twenty-one".