816561648 has 280 divisors, whose sum is σ = 2768105568. Its totient is φ = 228427776.

The previous prime is 816561637. The next prime is 816561661. The reversal of 816561648 is 846165618.

816561648 is a `hidden beast` number, since 81 + 6 + 561 + 6 + 4 + 8 = 666.

It is a super-3 number, since 3×816561648³ (a number of 28 digits) contains 333 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 (17) of ones.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 5960236 + ... + 5960372.

Almost surely, 2^816561648 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 816561648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1384052784).

816561648 is an abundant number, since it is smaller than the sum of its proper divisors (1951543920).

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

816561648 is a wasteful number, since it uses less digits than its factorization.

816561648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243 (or 222 counting only the distinct ones).

The product of its digits is 276480, while the sum is 45.

The square root of 816561648 is about 28575.5428294897. The cubic root of 816561648 is about 934.6800922594.

The spelling of 816561648 in words is "eight hundred sixteen million, five hundred sixty-one thousand, six hundred forty-eight".