691681454640 has 480 divisors, whose sum is σ = 2585223463680. Its totient is φ = 164316211200.

The previous prime is 691681454623. The next prime is 691681454669. The reversal of 691681454640 is 46454186196.

691681454640 is a `hidden beast` number, since 6 + 9 + 16 + 81 + 4 + 546 + 4 + 0 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 136720431 + ... + 136725489.

It is an arithmetic number, because the mean of its divisors is an integer number (5385882216).

Almost surely, 2^691681454640 is an apocalyptic number.

691681454640 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 691681454640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1292611731840).

691681454640 is an abundant number, since it is smaller than the sum of its proper divisors (1893542009040).

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

691681454640 is a wasteful number, since it uses less digits than its factorization.

691681454640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5433 (or 5424 counting only the distinct ones).

The product of its (nonzero) digits is 4976640, while the sum is 54.

The spelling of 691681454640 in words is "six hundred ninety-one billion, six hundred eighty-one million, four hundred fifty-four thousand, six hundred forty".