78260721 has 16 divisors (see below), whose sum is σ = 130096128. Its totient is φ = 40654800.

The previous prime is 78260719. The next prime is 78260729. The reversal of 78260721 is 12706287.

It is not a de Polignac number, because 78260721 - 2¹ = 78260719 is a prime.

It is a super-2 number, since 2×78260721² = 12249480902879682, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (78260729) 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 15 ways as a sum of consecutive naturals, for example, 169165 + ... + 169626.

It is an arithmetic number, because the mean of its divisors is an integer number (8131008).

Almost surely, 2^78260721 is an apocalyptic number.

It is an amenable number.

78260721 is a deficient number, since it is larger than the sum of its proper divisors (51835407).

78260721 is a wasteful number, since it uses less digits than its factorization.

78260721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338812.

The product of its (nonzero) digits is 9408, while the sum is 33.

The square root of 78260721 is about 8846.5089724704. The cubic root of 78260721 is about 427.7413950779.

The spelling of 78260721 in words is "seventy-eight million, two hundred sixty thousand, seven hundred twenty-one".