77945221 has 8 divisors (see below), whose sum is σ = 83459160. Its totient is φ = 72534528.

The previous prime is 77945209. The next prime is 77945227. The reversal of 77945221 is 12254977.

It can be written as a sum of positive squares in 4 ways, for example, as 30404196 + 47541025 = 5514^2 + 6895^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 77945221 - 2¹³ = 77937029 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77945227) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24246 + ... + 27271.

It is an arithmetic number, because the mean of its divisors is an integer number (10432395).

Almost surely, 2^77945221 is an apocalyptic number.

It is an amenable number.

77945221 is a deficient number, since it is larger than the sum of its proper divisors (5513939).

77945221 is a wasteful number, since it uses less digits than its factorization.

77945221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51623.

The product of its digits is 35280, while the sum is 37.

The square root of 77945221 is about 8828.6590714559. The cubic root of 77945221 is about 427.1658225363.

The spelling of 77945221 in words is "seventy-seven million, nine hundred forty-five thousand, two hundred twenty-one".