684891901 has 4 divisors (see below), whose sum is σ = 685506172. Its totient is φ = 684277632.

The previous prime is 684891887. The next prime is 684891919. The reversal of 684891901 is 109198486.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 109198486 = 2 ⋅54599243.

It can be written as a sum of positive squares in 2 ways, for example, as 407636100 + 277255801 = 20190^2 + 16651^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-684891901 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684891301) 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, 305460 + ... + 307693.

It is an arithmetic number, because the mean of its divisors is an integer number (171376543).

Almost surely, 2^684891901 is an apocalyptic number.

It is an amenable number.

684891901 is a deficient number, since it is larger than the sum of its proper divisors (614271).

684891901 is a wasteful number, since it uses less digits than its factorization.

684891901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 614270.

The product of its (nonzero) digits is 124416, while the sum is 46.

The square root of 684891901 is about 26170.4394498831. The cubic root of 684891901 is about 881.4696091955.

The spelling of 684891901 in words is "six hundred eighty-four million, eight hundred ninety-one thousand, nine hundred one".