78057921 has 4 divisors (see below), whose sum is σ = 104077232. Its totient is φ = 52038612.

The previous prime is 78057919. The next prime is 78057977. The reversal of 78057921 is 12975087.

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.

It is not a de Polignac number, because 78057921 - 2¹ = 78057919 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 78057921.

It is not an unprimeable number, because it can be changed into a prime (78057911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13009651 + ... + 13009656.

It is an arithmetic number, because the mean of its divisors is an integer number (26019308).

Almost surely, 2^78057921 is an apocalyptic number.

It is an amenable number.

78057921 is a deficient number, since it is larger than the sum of its proper divisors (26019311).

78057921 is a wasteful number, since it uses less digits than its factorization.

78057921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26019310.

The product of its (nonzero) digits is 35280, while the sum is 39.

The square root of 78057921 is about 8835.0393887068. The cubic root of 78057921 is about 427.3716012604.

The spelling of 78057921 in words is "seventy-eight million, fifty-seven thousand, nine hundred twenty-one".