684640959 has 4 divisors (see below), whose sum is σ = 912854616. Its totient is φ = 456427304.

The previous prime is 684640951. The next prime is 684640967. The reversal of 684640959 is 959046486.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (684640951) and next prime (684640967).

It is a cyclic number.

It is not a de Polignac number, because 684640959 - 2³ = 684640951 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684640951) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 114106824 + ... + 114106829.

It is an arithmetic number, because the mean of its divisors is an integer number (228213654).

Almost surely, 2^684640959 is an apocalyptic number.

684640959 is a deficient number, since it is larger than the sum of its proper divisors (228213657).

684640959 is a wasteful number, since it uses less digits than its factorization.

684640959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228213656.

The product of its (nonzero) digits is 1866240, while the sum is 51.

The square root of 684640959 is about 26165.6446318450. The cubic root of 684640959 is about 881.3619402493.

The spelling of 684640959 in words is "six hundred eighty-four million, six hundred forty thousand, nine hundred fifty-nine".