78626821 has 12 divisors (see below), whose sum is σ = 98500332. Its totient is φ = 62209728.

The previous prime is 78626803. The next prime is 78626827. The reversal of 78626821 is 12862687.

It can be written as a sum of positive squares in 2 ways, for example, as 29430625 + 49196196 = 5425^2 + 7014^2 .

It is not a de Polignac number, because 78626821 - 2¹³ = 78618629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78626827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 61080 + ... + 62353.

It is an arithmetic number, because the mean of its divisors is an integer number (8208361).

Almost surely, 2^78626821 is an apocalyptic number.

It is an amenable number.

78626821 is a deficient number, since it is larger than the sum of its proper divisors (19873511).

78626821 is a wasteful number, since it uses less digits than its factorization.

78626821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123460 (or 123453 counting only the distinct ones).

The product of its digits is 64512, while the sum is 40.

The square root of 78626821 is about 8867.1766081431. The cubic root of 78626821 is about 428.4073424917.

The spelling of 78626821 in words is "seventy-eight million, six hundred twenty-six thousand, eight hundred twenty-one".