81647541 has 16 divisors (see below), whose sum is σ = 127326400. Its totient is φ = 51566544.

The previous prime is 81647537. The next prime is 81647543. The reversal of 81647541 is 14574618.

It is a happy number.

81647541 is a `hidden beast` number, since 8 + 1 + 647 + 5 + 4 + 1 = 666.

It is not a de Polignac number, because 81647541 - 2² = 81647537 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81647496 and 81647505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81647543) 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, 79066 + ... + 80091.

It is an arithmetic number, because the mean of its divisors is an integer number (7957900).

Almost surely, 2^81647541 is an apocalyptic number.

It is an amenable number.

81647541 is a deficient number, since it is larger than the sum of its proper divisors (45678859).

81647541 is a wasteful number, since it uses less digits than its factorization.

81647541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159185 (or 159179 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 81647541 is about 9035.9028879244. The cubic root of 81647541 is about 433.8247946052.

The spelling of 81647541 in words is "eighty-one million, six hundred forty-seven thousand, five hundred forty-one".