721681610540 has 192 divisors, whose sum is σ = 1769577062400. Its totient is φ = 244464480000.

The previous prime is 721681610473. The next prime is 721681610561. The reversal of 721681610540 is 45016186127.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 82880867 + ... + 82889573.

It is an arithmetic number, because the mean of its divisors is an integer number (9216547200).

Almost surely, 2^721681610540 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 721681610540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (884788531200).

721681610540 is an abundant number, since it is smaller than the sum of its proper divisors (1047895451860).

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

721681610540 is a wasteful number, since it uses less digits than its factorization.

721681610540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9076 (or 9074 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 41.

Adding to 721681610540 its reverse (45016186127), we get a palindrome (766697796667).

The spelling of 721681610540 in words is "seven hundred twenty-one billion, six hundred eighty-one million, six hundred ten thousand, five hundred forty".