77221021 has 8 divisors (see below), whose sum is σ = 82608120. Its totient is φ = 71927808.

The previous prime is 77221019. The next prime is 77221049. The reversal of 77221021 is 12012277.

It can be written as a sum of positive squares in 4 ways, for example, as 5225796 + 71995225 = 2286^2 + 8485^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 77221021 - 2¹ = 77221019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 77220983 and 77221001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77221621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21766 + ... + 25063.

It is an arithmetic number, because the mean of its divisors is an integer number (10326015).

Almost surely, 2^77221021 is an apocalyptic number.

It is an amenable number.

77221021 is a deficient number, since it is larger than the sum of its proper divisors (5387099).

77221021 is a wasteful number, since it uses less digits than its factorization.

77221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46943.

The product of its (nonzero) digits is 392, while the sum is 22.

The square root of 77221021 is about 8787.5492032762. The cubic root of 77221021 is about 425.8387514507.

Adding to 77221021 its reverse (12012277), we get a palindrome (89233298).

The spelling of 77221021 in words is "seventy-seven million, two hundred twenty-one thousand, twenty-one".