816405660 has 216 divisors, whose sum is σ = 2904554016. Its totient is φ = 185068800.

The previous prime is 816405643. The next prime is 816405683. The reversal of 816405660 is 66504618.

816405660 is a `hidden beast` number, since 8 + 1 + 640 + 5 + 6 + 6 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1331514 + ... + 1332126.

Almost surely, 2^816405660 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 816405660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1452277008).

816405660 is an abundant number, since it is smaller than the sum of its proper divisors (2088148356).

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

816405660 is a wasteful number, since it uses less digits than its factorization.

816405660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 793 (or 781 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 816405660 is about 28572.8133021584. The cubic root of 816405660 is about 934.6205710693.

The spelling of 816405660 in words is "eight hundred sixteen million, four hundred five thousand, six hundred sixty".