816857640 has 48 divisors (see below), whose sum is σ = 2654788500. Its totient is φ = 217828608.

The previous prime is 816857611. The next prime is 816857647. The reversal of 816857640 is 46758618.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 788149476 + 28708164 = 28074^2 + 5358^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (816857647) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1134165 + ... + 1134884.

Almost surely, 2^816857640 is an apocalyptic number.

It is an amenable number.

816857640 is an abundant number, since it is smaller than the sum of its proper divisors (1837930860).

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

816857640 is a wasteful number, since it uses less digits than its factorization.

816857640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2269066 (or 2269059 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 45.

The square root of 816857640 is about 28580.7214744485. The cubic root of 816857640 is about 934.7930147024.

The spelling of 816857640 in words is "eight hundred sixteen million, eight hundred fifty-seven thousand, six hundred forty".