78081221 has 8 divisors (see below), whose sum is σ = 82940760. Its totient is φ = 73251328.

The previous prime is 78081173. The next prime is 78081233. The reversal of 78081221 is 12218087.

It can be written as a sum of positive squares in 4 ways, for example, as 376996 + 77704225 = 614^2 + 8815^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78081221 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 (78081271) 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, 1856 + ... + 12633.

It is an arithmetic number, because the mean of its divisors is an integer number (10367595).

Almost surely, 2^78081221 is an apocalyptic number.

It is an amenable number.

78081221 is a deficient number, since it is larger than the sum of its proper divisors (4859539).

78081221 is a wasteful number, since it uses less digits than its factorization.

78081221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14823.

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 78081221 is about 8836.3579035709. The cubic root of 78081221 is about 427.4141199762.

The spelling of 78081221 in words is "seventy-eight million, eighty-one thousand, two hundred twenty-one".