78270721 has 4 divisors (see below), whose sum is σ = 78317872. Its totient is φ = 78223572.

The previous prime is 78270713. The next prime is 78270733. The reversal of 78270721 is 12707287.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12707287 = 67 ⋅189661.

It is a cyclic number.

It is not a de Polignac number, because 78270721 - 2³ = 78270713 is a prime.

It is a super-2 number, since 2×78270721² = 12252611531719682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78270781) 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, 20991 + ... + 24436.

It is an arithmetic number, because the mean of its divisors is an integer number (19579468).

Almost surely, 2^78270721 is an apocalyptic number.

It is an amenable number.

78270721 is a deficient number, since it is larger than the sum of its proper divisors (47151).

78270721 is a wasteful number, since it uses less digits than its factorization.

78270721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47150.

The product of its (nonzero) digits is 10976, while the sum is 34.

The square root of 78270721 is about 8847.0741491185. The cubic root of 78270721 is about 427.7596129516.

It can be divided in two parts, 7 and 8270721, that added together give a palindrome (8270728).

The spelling of 78270721 in words is "seventy-eight million, two hundred seventy thousand, seven hundred twenty-one".