684461721 has 4 divisors (see below), whose sum is σ = 912615632. Its totient is φ = 456307812.

The previous prime is 684461711. The next prime is 684461759. The reversal of 684461721 is 127164486.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 684461721 - 2¹³ = 684453529 is a prime.

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 684461721.

It is not an unprimeable number, because it can be changed into a prime (684461711) 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 3 ways as a sum of consecutive naturals, for example, 114076951 + ... + 114076956.

It is an arithmetic number, because the mean of its divisors is an integer number (228153908).

Almost surely, 2^684461721 is an apocalyptic number.

It is an amenable number.

684461721 is a deficient number, since it is larger than the sum of its proper divisors (228153911).

684461721 is a wasteful number, since it uses less digits than its factorization.

684461721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228153910.

The product of its digits is 64512, while the sum is 39.

The square root of 684461721 is about 26162.2193439318. The cubic root of 684461721 is about 881.2850204482.

The spelling of 684461721 in words is "six hundred eighty-four million, four hundred sixty-one thousand, seven hundred twenty-one".