781497731664 has 480 divisors, whose sum is σ = 2535916690944. Its totient is φ = 231443619840.

The previous prime is 781497731639. The next prime is 781497731687. The reversal of 781497731664 is 466137794187.

781497731664 is a `hidden beast` number, since 7 + 8 + 1 + 497 + 73 + 16 + 64 = 666.

It is a super-2 number, since 2×781497731664² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

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 95 ways as a sum of consecutive naturals, for example, 144906952 + ... + 144912344.

Almost surely, 2^781497731664 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 781497731664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1267958345472).

781497731664 is an abundant number, since it is smaller than the sum of its proper divisors (1754418959280).

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

781497731664 is a wasteful number, since it uses less digits than its factorization.

781497731664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5537 (or 5519 counting only the distinct ones).

The product of its digits is 42674688, while the sum is 63.

The spelling of 781497731664 in words is "seven hundred eighty-one billion, four hundred ninety-seven million, seven hundred thirty-one thousand, six hundred sixty-four".