78434021 has 4 divisors (see below), whose sum is σ = 80258112. Its totient is φ = 76609932.

The previous prime is 78434003. The next prime is 78434029. The reversal of 78434021 is 12043487.

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: 12043487 = 607 ⋅19841.

It is a cyclic number.

It is not a de Polignac number, because 78434021 - 2¹⁰ = 78432997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78434029) 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, 911981 + ... + 912066.

It is an arithmetic number, because the mean of its divisors is an integer number (20064528).

Almost surely, 2^78434021 is an apocalyptic number.

It is an amenable number.

78434021 is a deficient number, since it is larger than the sum of its proper divisors (1824091).

78434021 is a wasteful number, since it uses less digits than its factorization.

78434021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1824090.

The product of its (nonzero) digits is 5376, while the sum is 29.

The square root of 78434021 is about 8856.2983802489. The cubic root of 78434021 is about 428.0568915116.

The spelling of 78434021 in words is "seventy-eight million, four hundred thirty-four thousand, twenty-one".