78520421 has 8 divisors (see below), whose sum is σ = 89943744. Its totient is φ = 67148640.

The previous prime is 78520411. The next prime is 78520447. The reversal of 78520421 is 12402587.

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

It is a cyclic number.

It is not a de Polignac number, because 78520421 - 2⁶ = 78520357 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78520411) 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 7 ways as a sum of consecutive naturals, for example, 9560 + ... + 15761.

It is an arithmetic number, because the mean of its divisors is an integer number (11242968).

Almost surely, 2^78520421 is an apocalyptic number.

It is an amenable number.

78520421 is a deficient number, since it is larger than the sum of its proper divisors (11423323).

78520421 is a wasteful number, since it uses less digits than its factorization.

78520421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25771.

The product of its (nonzero) digits is 4480, while the sum is 29.

The square root of 78520421 is about 8861.1749220970. The cubic root of 78520421 is about 428.2140110164.

The spelling of 78520421 in words is "seventy-eight million, five hundred twenty thousand, four hundred twenty-one".