81311547 has 8 divisors (see below), whose sum is σ = 109429056. Its totient is φ = 53700872.

The previous prime is 81311539. The next prime is 81311579. The reversal of 81311547 is 74511318.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81311547 - 2³ = 81311539 is a prime.

It is a super-2 number, since 2×81311547² = 13223135351066418, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81311147) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 126333 + ... + 126974.

It is an arithmetic number, because the mean of its divisors is an integer number (13678632).

Almost surely, 2^81311547 is an apocalyptic number.

81311547 is a deficient number, since it is larger than the sum of its proper divisors (28117509).

81311547 is a wasteful number, since it uses less digits than its factorization.

81311547 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 253417.

The product of its digits is 3360, while the sum is 30.

The square root of 81311547 is about 9017.2915556724. The cubic root of 81311547 is about 433.2288879770.

The spelling of 81311547 in words is "eighty-one million, three hundred eleven thousand, five hundred forty-seven".