81163601 has 4 divisors (see below), whose sum is σ = 81192612. Its totient is φ = 81134592.

The previous prime is 81163597. The next prime is 81163633. The reversal of 81163601 is 10636118.

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 67650625 + 13512976 = 8225^2 + 3676^2 .

It is a cyclic number.

It is not a de Polignac number, because 81163601 - 2² = 81163597 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81103601) 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, 9800 + ... + 16073.

It is an arithmetic number, because the mean of its divisors is an integer number (20298153).

Almost surely, 2^81163601 is an apocalyptic number.

It is an amenable number.

81163601 is a deficient number, since it is larger than the sum of its proper divisors (29011).

81163601 is a wasteful number, since it uses less digits than its factorization.

81163601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29010.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 81163601 is about 9009.0843596894. The cubic root of 81163601 is about 432.9659757750.

Adding to 81163601 its reverse (10636118), we get a palindrome (91799719).

The spelling of 81163601 in words is "eighty-one million, one hundred sixty-three thousand, six hundred one".