81231601 has 16 divisors (see below), whose sum is σ = 91238400. Its totient is φ = 71683920.

The previous prime is 81231599. The next prime is 81231611. The reversal of 81231601 is 10613218.

It is not a de Polignac number, because 81231601 - 2¹ = 81231599 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81231611) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 93696 + ... + 94558.

It is an arithmetic number, because the mean of its divisors is an integer number (5702400).

Almost surely, 2^81231601 is an apocalyptic number.

It is an amenable number.

81231601 is a deficient number, since it is larger than the sum of its proper divisors (10006799).

81231601 is a wasteful number, since it uses less digits than its factorization.

81231601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1116.

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 81231601 is about 9012.8575379843. The cubic root of 81231601 is about 433.0868570058.

Adding to 81231601 its reverse (10613218), we get a palindrome (91844819).

The spelling of 81231601 in words is "eighty-one million, two hundred thirty-one thousand, six hundred one".