78505620821 has 8 divisors (see below), whose sum is σ = 79120960800. Its totient is φ = 77891003280.

The previous prime is 78505620797. The next prime is 78505620847. The reversal of 78505620821 is 12802650587.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78505620821 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78505020821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38615 + ... + 398123.

It is an arithmetic number, because the mean of its divisors is an integer number (9890120100).

Almost surely, 2^78505620821 is an apocalyptic number.

It is an amenable number.

78505620821 is a deficient number, since it is larger than the sum of its proper divisors (615339979).

78505620821 is a wasteful number, since it uses less digits than its factorization.

78505620821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 361219.

The product of its (nonzero) digits is 268800, while the sum is 44.

The spelling of 78505620821 in words is "seventy-eight billion, five hundred five million, six hundred twenty thousand, eight hundred twenty-one".