77804865221 has 4 divisors (see below), whose sum is σ = 81187685472. Its totient is φ = 74422044972.

The previous prime is 77804865197. The next prime is 77804865263. The reversal of 77804865221 is 12256840877.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 77804865221 - 2¹⁴ = 77804848837 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 77804865221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77804865421) 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, 1691410091 + ... + 1691410136.

It is an arithmetic number, because the mean of its divisors is an integer number (20296921368).

Almost surely, 2^77804865221 is an apocalyptic number.

It is an amenable number.

77804865221 is a deficient number, since it is larger than the sum of its proper divisors (3382820251).

77804865221 is a wasteful number, since it uses less digits than its factorization.

77804865221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3382820250.

The product of its (nonzero) digits is 1505280, while the sum is 50.

The spelling of 77804865221 in words is "seventy-seven billion, eight hundred four million, eight hundred sixty-five thousand, two hundred twenty-one".