77721773 has 8 divisors (see below), whose sum is σ = 84301560. Its totient is φ = 71365120.

The previous prime is 77721767. The next prime is 77721803. The reversal of 77721773 is 37712777.

It can be written as a sum of positive squares in 4 ways, for example, as 316969 + 77404804 = 563^2 + 8798^2 .

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 77721773 - 2⁴ = 77721757 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

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 77721773.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77721173) 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, 55058 + ... + 56451.

It is an arithmetic number, because the mean of its divisors is an integer number (10537695).

Almost surely, 2^77721773 is an apocalyptic number.

It is an amenable number.

77721773 is a deficient number, since it is larger than the sum of its proper divisors (6579787).

77721773 is a wasteful number, since it uses less digits than its factorization.

77721773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111567.

The product of its digits is 100842, while the sum is 41.

The square root of 77721773 is about 8815.9952926485. The cubic root of 77721773 is about 426.7572419877.

The spelling of 77721773 in words is "seventy-seven million, seven hundred twenty-one thousand, seven hundred seventy-three".