681540 has 48 divisors (see below), whose sum is σ = 1966272. Its totient is φ = 176256.

The previous prime is 681539. The next prime is 681557. The reversal of 681540 is 45186.

681540 = T₂₅₁ + T₂₅₂ + ... + T₂₇₀.

It is a nialpdrome in base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 681540.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2067 + ... + 2373.

It is an arithmetic number, because the mean of its divisors is an integer number (40964).

2⁶⁸¹⁵⁴⁰ is an apocalyptic number.

681540 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 681540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (983136).

681540 is an abundant number, since it is smaller than the sum of its proper divisors (1284732).

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

681540 is a wasteful number, since it uses less digits than its factorization.

681540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356 (or 354 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 681540 is about 825.5543592036. The cubic root of 681540 is about 88.0029268999.

It can be divided in two parts, 681 and 540, that added together give a palindrome (1221).

The spelling of 681540 in words is "six hundred eighty-one thousand, five hundred forty".