677721 has 12 divisors (see below), whose sum is σ = 993776. Its totient is φ = 410520.

The previous prime is 677717. The next prime is 677737. The reversal of 677721 is 127776.

It is a happy number.

It is not a de Polignac number, because 677721 - 2² = 677717 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 677721.

It is not an unprimeable number, because it can be changed into a prime (677791) 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 11 ways as a sum of consecutive naturals, for example, 571 + ... + 1296.

2⁶⁷⁷⁷²¹ is an apocalyptic number.

It is an amenable number.

677721 is a deficient number, since it is larger than the sum of its proper divisors (316055).

677721 is a wasteful number, since it uses less digits than its factorization.

677721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1892 (or 1881 counting only the distinct ones).

The product of its digits is 4116, while the sum is 30.

The square root of 677721 is about 823.2381186510. The cubic root of 677721 is about 87.8382445212.

Subtracting from 677721 its reverse (127776), we obtain a palindrome (549945).

The spelling of 677721 in words is "six hundred seventy-seven thousand, seven hundred twenty-one".