681520 has 40 divisors (see below), whose sum is σ = 1812384. Its totient is φ = 233472.

The previous prime is 681497. The next prime is 681521. The reversal of 681520 is 25186.

681520 = T₃₀₅ + T₃₀₆ + ... + T₃₁₈.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is a nialpdrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 681491 and 681500.

It is not an unprimeable number, because it can be changed into a prime (681521) by changing a digit.

681520 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49 + ... + 1168.

2⁶⁸¹⁵²⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 681520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (906192).

681520 is an abundant number, since it is smaller than the sum of its proper divisors (1130864).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

681520 is a wasteful number, since it uses less digits than its factorization.

681520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1237 (or 1231 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 681520 is about 825.5422460420. The cubic root of 681520 is about 88.0020660672.

The spelling of 681520 in words is "six hundred eighty-one thousand, five hundred twenty".