78220381 has 4 divisors (see below), whose sum is σ = 78745500. Its totient is φ = 77695264.

The previous prime is 78220379. The next prime is 78220433. The reversal of 78220381 is 18302287.

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 32387481 + 45832900 = 5691^2 + 6770^2 .

It is a cyclic number.

It is not a de Polignac number, because 78220381 - 2¹ = 78220379 is a prime.

It is a super-2 number, since 2×78220381² = 12236856007570322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78220481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 262336 + ... + 262633.

It is an arithmetic number, because the mean of its divisors is an integer number (19686375).

Almost surely, 2^78220381 is an apocalyptic number.

It is an amenable number.

78220381 is a deficient number, since it is larger than the sum of its proper divisors (525119).

78220381 is a wasteful number, since it uses less digits than its factorization.

78220381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 525118.

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 78220381 is about 8844.2286831583. The cubic root of 78220381 is about 427.6678884143.

The spelling of 78220381 in words is "seventy-eight million, two hundred twenty thousand, three hundred eighty-one".