689713921 has 4 divisors (see below), whose sum is σ = 742768852. Its totient is φ = 636658992.

The previous prime is 689713909. The next prime is 689713939. The reversal of 689713921 is 129317986.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 297079696 + 392634225 = 17236^2 + 19815^2 .

It is a cyclic number.

It is not a de Polignac number, because 689713921 - 2¹³ = 689705729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (689713991) 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 3 ways as a sum of consecutive naturals, for example, 26527446 + ... + 26527471.

It is an arithmetic number, because the mean of its divisors is an integer number (185692213).

Almost surely, 2^689713921 is an apocalyptic number.

It is an amenable number.

689713921 is a deficient number, since it is larger than the sum of its proper divisors (53054931).

689713921 is a wasteful number, since it uses less digits than its factorization.

689713921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53054930.

The product of its digits is 163296, while the sum is 46.

The square root of 689713921 is about 26262.4050878818. The cubic root of 689713921 is about 883.5334520215.

It can be divided in two parts, 689 and 713921, that added together give a triangular number (714610 = T₁₁₉₅).

The spelling of 689713921 in words is "six hundred eighty-nine million, seven hundred thirteen thousand, nine hundred twenty-one".