81181245 has 16 divisors (see below), whose sum is σ = 130312512. Its totient is φ = 43155840.

The previous prime is 81181229. The next prime is 81181249. The reversal of 81181245 is 54218118.

It is a happy number.

It is not a de Polignac number, because 81181245 - 2⁴ = 81181229 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81181249) 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, 3951 + ... + 13340.

It is an arithmetic number, because the mean of its divisors is an integer number (8144532).

Almost surely, 2^81181245 is an apocalyptic number.

It is an amenable number.

81181245 is a deficient number, since it is larger than the sum of its proper divisors (49131267).

81181245 is a wasteful number, since it uses less digits than its factorization.

81181245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17612.

The product of its digits is 2560, while the sum is 30.

The square root of 81181245 is about 9010.0635402865. The cubic root of 81181245 is about 432.9973473837.

The spelling of 81181245 in words is "eighty-one million, one hundred eighty-one thousand, two hundred forty-five".