77821218 has 12 divisors (see below), whose sum is σ = 168612678. Its totient is φ = 25940400.

The previous prime is 77821217. The next prime is 77821229. The reversal of 77821218 is 81212877.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 52751169 + 25070049 = 7263^2 + 5007^2 .

It is a super-2 number, since 2×77821218² = 12112283942007048, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (77821217) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2161683 + ... + 2161718.

Almost surely, 2^77821218 is an apocalyptic number.

77821218 is an abundant number, since it is smaller than the sum of its proper divisors (90791460).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

77821218 is a wasteful number, since it uses less digits than its factorization.

77821218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4323409 (or 4323406 counting only the distinct ones).

The product of its digits is 12544, while the sum is 36.

The square root of 77821218 is about 8821.6335221998. The cubic root of 77821218 is about 426.9391763628.

The spelling of 77821218 in words is "seventy-seven million, eight hundred twenty-one thousand, two hundred eighteen".