799661581 has 4 divisors (see below), whose sum is σ = 819165564. Its totient is φ = 780157600.

The previous prime is 799661561. The next prime is 799661587. The reversal of 799661581 is 185166997.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 185166997 = 23 ⋅8050739.

It can be written as a sum of positive squares in 2 ways, for example, as 345588100 + 454073481 = 18590^2 + 21309^2 .

It is a cyclic number.

It is not a de Polignac number, because 799661581 - 2¹¹ = 799659533 is a prime.

It is a super-2 number, since 2×799661581² = 1278917288254839122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (799661587) 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, 9751930 + ... + 9752011.

It is an arithmetic number, because the mean of its divisors is an integer number (204791391).

Almost surely, 2^799661581 is an apocalyptic number.

It is an amenable number.

799661581 is a deficient number, since it is larger than the sum of its proper divisors (19503983).

799661581 is a wasteful number, since it uses less digits than its factorization.

799661581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19503982.

The product of its digits is 816480, while the sum is 52.

The square root of 799661581 is about 28278.2881554029. The cubic root of 799661581 is about 928.1868481060.

The spelling of 799661581 in words is "seven hundred ninety-nine million, six hundred sixty-one thousand, five hundred eighty-one".