681531648 has 144 divisors (see below), whose sum is σ = 2084683776. Its totient is φ = 193628160.

The previous prime is 681531647. The next prime is 681531661. The reversal of 681531648 is 846135186.

It is a super-3 number, since 3×681531648³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681531647) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1779265 + ... + 1779647.

Almost surely, 2^681531648 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 681531648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1042341888).

681531648 is an abundant number, since it is smaller than the sum of its proper divisors (1403152128).

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

681531648 is a wasteful number, since it uses less digits than its factorization.

681531648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 740 (or 726 counting only the distinct ones).

The product of its digits is 138240, while the sum is 42.

The square root of 681531648 is about 26106.1611118908. The cubic root of 681531648 is about 880.0256741821.

The spelling of 681531648 in words is "six hundred eighty-one million, five hundred thirty-one thousand, six hundred forty-eight".