781535664 has 480 divisors, whose sum is σ = 2939256320. Its totient is φ = 188116992.

The previous prime is 781535627. The next prime is 781535669. The reversal of 781535664 is 466535187.

781535664 is a `hidden beast` number, since 7 + 81 + 5 + 3 + 566 + 4 = 666.

It is a super-2 number, since 2×781535664² = 1221595988207841792, which contains 22 as substring.

Its product of digits (604800) is a multiple of the sum of its prime divisors (160).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781535669) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 10705932 + ... + 10706004.

Almost surely, 2^781535664 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 781535664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1469628160).

781535664 is an abundant number, since it is smaller than the sum of its proper divisors (2157720656).

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

781535664 is a wasteful number, since it uses less digits than its factorization.

781535664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169 (or 160 counting only the distinct ones).

The product of its digits is 604800, while the sum is 45.

The square root of 781535664 is about 27955.9593646864. The cubic root of 781535664 is about 921.1201164660.

The spelling of 781535664 in words is "seven hundred eighty-one million, five hundred thirty-five thousand, six hundred sixty-four".