77638221 has 6 divisors (see below), whose sum is σ = 112144110. Its totient is φ = 51758808.

The previous prime is 77638217. The next prime is 77638241. The reversal of 77638221 is 12283677.

It can be written as a sum of positive squares in only one way, i.e., 71318025 + 6320196 = 8445^2 + 2514^2 .

It is not a de Polignac number, because 77638221 - 2² = 77638217 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77638241) 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 5 ways as a sum of consecutive naturals, for example, 4313226 + ... + 4313243.

It is an arithmetic number, because the mean of its divisors is an integer number (18690685).

Almost surely, 2^77638221 is an apocalyptic number.

It is an amenable number.

77638221 is a deficient number, since it is larger than the sum of its proper divisors (34505889).

77638221 is a wasteful number, since it uses less digits than its factorization.

77638221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8626475 (or 8626472 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 77638221 is about 8811.2553589145. The cubic root of 77638221 is about 426.6042638093.

The spelling of 77638221 in words is "seventy-seven million, six hundred thirty-eight thousand, two hundred twenty-one".