816805397 has 4 divisors (see below), whose sum is σ = 821318316. Its totient is φ = 812292480.

The previous prime is 816805369. The next prime is 816805427. The reversal of 816805397 is 793508618.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 225780676 + 591024721 = 15026^2 + 24311^2 .

It is a cyclic number.

It is not a de Polignac number, because 816805397 - 2¹⁸ = 816543253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816855397) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2256188 + ... + 2256549.

It is an arithmetic number, because the mean of its divisors is an integer number (205329579).

Almost surely, 2^816805397 is an apocalyptic number.

It is an amenable number.

816805397 is a deficient number, since it is larger than the sum of its proper divisors (4512919).

816805397 is a wasteful number, since it uses less digits than its factorization.

816805397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4512918.

The product of its (nonzero) digits is 362880, while the sum is 47.

The square root of 816805397 is about 28579.8075046002. The cubic root of 816805397 is about 934.7730857167.

The spelling of 816805397 in words is "eight hundred sixteen million, eight hundred five thousand, three hundred ninety-seven".