77716221 has 8 divisors (see below), whose sum is σ = 113041824. Its totient is φ = 47100720.

The previous prime is 77716217. The next prime is 77716229. The reversal of 77716221 is 12261777.

It is a happy number.

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

It is not a de Polignac number, because 77716221 - 2² = 77716217 is a prime.

It is a super-2 number, since 2×77716221² = 12079622013041682, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 2355037 = 77716221 / (7 + 7 + 7 + 1 + 6 + 2 + 2 + 1).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77716229) 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, 1177486 + ... + 1177551.

It is an arithmetic number, because the mean of its divisors is an integer number (14130228).

Almost surely, 2^77716221 is an apocalyptic number.

It is an amenable number.

77716221 is a deficient number, since it is larger than the sum of its proper divisors (35325603).

77716221 is a wasteful number, since it uses less digits than its factorization.

77716221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2355051.

The product of its digits is 8232, while the sum is 33.

The square root of 77716221 is about 8815.6804048241. The cubic root of 77716221 is about 426.7470800449.

Adding to 77716221 its reverse (12261777), we get a palindrome (89977998).

The spelling of 77716221 in words is "seventy-seven million, seven hundred sixteen thousand, two hundred twenty-one".