78235821 has 16 divisors (see below), whose sum is σ = 116107200. Its totient is φ = 52066224.

The previous prime is 78235799. The next prime is 78235837. The reversal of 78235821 is 12853287.

78235821 is a `hidden beast` number, since 78 + 2 + 3 + 582 + 1 = 666.

It is not a de Polignac number, because 78235821 - 2¹⁴ = 78219437 is a prime.

It is a super-2 number, since 2×78235821² = 12241687375088082, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78235841) 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 15 ways as a sum of consecutive naturals, for example, 15595 + ... + 19991.

It is an arithmetic number, because the mean of its divisors is an integer number (7256700).

Almost surely, 2^78235821 is an apocalyptic number.

It is an amenable number.

78235821 is a deficient number, since it is larger than the sum of its proper divisors (37871379).

78235821 is a wasteful number, since it uses less digits than its factorization.

78235821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5065 (or 5059 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 78235821 is about 8845.1015257034. The cubic root of 78235821 is about 427.6960258285.

The spelling of 78235821 in words is "seventy-eight million, two hundred thirty-five thousand, eight hundred twenty-one".