78245221 has 4 divisors (see below), whose sum is σ = 78816492. Its totient is φ = 77673952.

The previous prime is 78245207. The next prime is 78245231. The reversal of 78245221 is 12254287.

It is a happy number.

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 24750625 + 53494596 = 4975^2 + 7314^2 .

It is a cyclic number.

It is not a de Polignac number, because 78245221 - 2²³ = 69856613 is a prime.

It is a super-2 number, since 2×78245221² = 12244629218677682, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78245201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 285430 + ... + 285703.

It is an arithmetic number, because the mean of its divisors is an integer number (19704123).

Almost surely, 2^78245221 is an apocalyptic number.

It is an amenable number.

78245221 is a deficient number, since it is larger than the sum of its proper divisors (571271).

78245221 is a wasteful number, since it uses less digits than its factorization.

78245221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 571270.

The product of its digits is 8960, while the sum is 31.

The square root of 78245221 is about 8845.6328773017. The cubic root of 78245221 is about 427.7131543066.

The spelling of 78245221 in words is "seventy-eight million, two hundred forty-five thousand, two hundred twenty-one".