78325721 has 4 divisors (see below), whose sum is σ = 78550500. Its totient is φ = 78100944.

The previous prime is 78325717. The next prime is 78325727. The reversal of 78325721 is 12752387.

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 25603600 + 52722121 = 5060^2 + 7261^2 .

It is a cyclic number.

It is not a de Polignac number, because 78325721 - 2² = 78325717 is a prime.

It is a super-2 number, since 2×78325721² = 12269837140339682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78325727) 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, 111866 + ... + 112563.

It is an arithmetic number, because the mean of its divisors is an integer number (19637625).

Almost surely, 2^78325721 is an apocalyptic number.

It is an amenable number.

78325721 is a deficient number, since it is larger than the sum of its proper divisors (224779).

78325721 is a wasteful number, since it uses less digits than its factorization.

78325721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 224778.

The product of its digits is 23520, while the sum is 35.

The square root of 78325721 is about 8850.1819755302. The cubic root of 78325721 is about 427.8597835300.

The spelling of 78325721 in words is "seventy-eight million, three hundred twenty-five thousand, seven hundred twenty-one".