81317388 has 12 divisors (see below), whose sum is σ = 189740600. Its totient is φ = 27105792.

The previous prime is 81317387. The next prime is 81317389. The reversal of 81317388 is 88371318.

It is an interprime number because it is at equal distance from previous prime (81317387) and next prime (81317389).

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×81317388² = 13225035182285088, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81317381) 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, 3388213 + ... + 3388236.

Almost surely, 2^81317388 is an apocalyptic number.

It is an amenable number.

81317388 is an abundant number, since it is smaller than the sum of its proper divisors (108423212).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81317388 is a wasteful number, since it uses less digits than its factorization.

81317388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6776456 (or 6776454 counting only the distinct ones).

The product of its digits is 32256, while the sum is 39.

The square root of 81317388 is about 9017.6154275950. The cubic root of 81317388 is about 433.2392613678.

The spelling of 81317388 in words is "eighty-one million, three hundred seventeen thousand, three hundred eighty-eight".