78054821 has 4 divisors (see below), whose sum is σ = 84059052. Its totient is φ = 72050592.

The previous prime is 78054763. The next prime is 78054853. The reversal of 78054821 is 12845087.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12845087 = 283 ⋅45389.

It can be written as a sum of positive squares in 2 ways, for example, as 3422500 + 74632321 = 1850^2 + 8639^2 .

It is a cyclic number.

It is not a de Polignac number, because 78054821 - 2¹⁸ = 77792677 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 (78054881) 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, 3002096 + ... + 3002121.

It is an arithmetic number, because the mean of its divisors is an integer number (21014763).

Almost surely, 2^78054821 is an apocalyptic number.

It is an amenable number.

78054821 is a deficient number, since it is larger than the sum of its proper divisors (6004231).

78054821 is a wasteful number, since it uses less digits than its factorization.

78054821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6004230.

The product of its (nonzero) digits is 17920, while the sum is 35.

The square root of 78054821 is about 8834.8639491505. The cubic root of 78054821 is about 427.3659436261.

The spelling of 78054821 in words is "seventy-eight million, fifty-four thousand, eight hundred twenty-one".