78437487421 has 4 divisors (see below), whose sum is σ = 78438103452. Its totient is φ = 78436871392.

The previous prime is 78437487383. The next prime is 78437487481. The reversal of 78437487421 is 12478473487.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12478473487 = 53197 ⋅234571.

It can be written as a sum of positive squares in 2 ways, for example, as 59725983321 + 18711504100 = 244389^2 + 136790^2 .

It is a cyclic number.

It is not a de Polignac number, because 78437487421 - 2¹⁹ = 78436963133 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 (78437487481) 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, 38296 + ... + 397921.

It is an arithmetic number, because the mean of its divisors is an integer number (19609525863).

Almost surely, 2^78437487421 is an apocalyptic number.

It is an amenable number.

78437487421 is a deficient number, since it is larger than the sum of its proper divisors (616031).

78437487421 is a wasteful number, since it uses less digits than its factorization.

78437487421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 616030.

The product of its digits is 8429568, while the sum is 55.

The spelling of 78437487421 in words is "seventy-eight billion, four hundred thirty-seven million, four hundred eighty-seven thousand, four hundred twenty-one".