815945681 has 8 divisors (see below), whose sum is σ = 825927840. Its totient is φ = 805981792.

The previous prime is 815945657. The next prime is 815945687. The reversal of 815945681 is 186549518.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 815945681 - 2²⁶ = 748836817 is a prime.

It is a super-2 number, since 2×815945681² = 1331534708685107522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (815945687) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 99566 + ... + 107448.

It is an arithmetic number, because the mean of its divisors is an integer number (103240980).

Almost surely, 2^815945681 is an apocalyptic number.

It is an amenable number.

815945681 is a deficient number, since it is larger than the sum of its proper divisors (9982159).

815945681 is a wasteful number, since it uses less digits than its factorization.

815945681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9135.

The product of its digits is 345600, while the sum is 47.

The square root of 815945681 is about 28564.7629256747. The cubic root of 815945681 is about 934.4450102253.

The spelling of 815945681 in words is "eight hundred fifteen million, nine hundred forty-five thousand, six hundred eighty-one".