819736640 has 56 divisors (see below), whose sum is σ = 1958397912. Its totient is φ = 326819840.

The previous prime is 819736597. The next prime is 819736679. The reversal of 819736640 is 46637918.

It can be written as a sum of positive squares in 4 ways, for example, as 861184 + 818875456 = 928^2 + 28616^2 .

It is a junction number, because it is equal to n+sod(n) for n = 819736591 and 819736600.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 97400 + ... + 105480.

Almost surely, 2^819736640 is an apocalyptic number.

819736640 is a gapful number since it is divisible by the number (80) 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 819736640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (979198956).

819736640 is an abundant number, since it is smaller than the sum of its proper divisors (1138661272).

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

819736640 is a wasteful number, since it uses less digits than its factorization.

819736640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8415 (or 8405 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 44.

The square root of 819736640 is about 28631.0432922030. The cubic root of 819736640 is about 935.8899473695.

The spelling of 819736640 in words is "eight hundred nineteen million, seven hundred thirty-six thousand, six hundred forty".