684188649 has 9 divisors (see below), whose sum is σ = 988385853. Its totient is φ = 456073452.

The previous prime is 684188641. The next prime is 684188663. The reversal of 684188649 is 946881486.

The square root of 684188649 is 26157.

It is a perfect power (a square), and thus also a powerful number.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 684188649 - 2³ = 684188641 is a prime.

It is a super-2 number, since 2×684188649² = 936228214840890402, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 684188595 and 684188604.

It is not an unprimeable number, because it can be changed into a prime (684188641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 74112 + ... + 82830.

Almost surely, 2^684188649 is an apocalyptic number.

684188649 is the 26157-th square number.

684188649 is the 13079-th centered octagonal number.

It is an amenable number.

684188649 is a deficient number, since it is larger than the sum of its proper divisors (304197204).

684188649 is an frugal number, since it uses more digits than its factorization.

684188649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17444 (or 8722 counting only the distinct ones).

The product of its digits is 2654208, while the sum is 54.

The cubic root of 684188649 is about 881.1678060657.

The spelling of 684188649 in words is "six hundred eighty-four million, one hundred eighty-eight thousand, six hundred forty-nine".