781371864 has 192 divisors, whose sum is σ = 2689290240. Its totient is φ = 199376640.

The previous prime is 781371863. The next prime is 781371881. The reversal of 781371864 is 468173187.

781371864 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×781371864² = 1221083979701668992, which contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781371863) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 201189 + ... + 205035.

It is an arithmetic number, because the mean of its divisors is an integer number (14006720).

Almost surely, 2^781371864 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 781371864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1344645120).

781371864 is an abundant number, since it is smaller than the sum of its proper divisors (1907918376).

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

781371864 is a wasteful number, since it uses less digits than its factorization.

781371864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3910 (or 3903 counting only the distinct ones).

The product of its digits is 225792, while the sum is 45.

The square root of 781371864 is about 27953.0296032469. The cubic root of 781371864 is about 921.0557602572.

The spelling of 781371864 in words is "seven hundred eighty-one million, three hundred seventy-one thousand, eight hundred sixty-four".