78452921 has 4 divisors (see below), whose sum is σ = 79261812. Its totient is φ = 77644032.

The previous prime is 78452911. The next prime is 78452939. The reversal of 78452921 is 12925487.

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 13875625 + 64577296 = 3725^2 + 8036^2 .

It is a cyclic number.

It is not a de Polignac number, because 78452921 - 2¹⁴ = 78436537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78452911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 404300 + ... + 404493.

It is an arithmetic number, because the mean of its divisors is an integer number (19815453).

Almost surely, 2^78452921 is an apocalyptic number.

It is an amenable number.

78452921 is a deficient number, since it is larger than the sum of its proper divisors (808891).

78452921 is an equidigital number, since it uses as much as digits as its factorization.

78452921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 808890.

The product of its digits is 40320, while the sum is 38.

The square root of 78452921 is about 8857.3653531962. The cubic root of 78452921 is about 428.0912712590.

The spelling of 78452921 in words is "seventy-eight million, four hundred fifty-two thousand, nine hundred twenty-one".