81481508 has 6 divisors (see below), whose sum is σ = 142592646. Its totient is φ = 40740752.

The previous prime is 81481501. The next prime is 81481513. The reversal of 81481508 is 80518418.

It can be written as a sum of positive squares in only one way, i.e., 46812964 + 34668544 = 6842^2 + 5888^2 .

It is a super-2 number, since 2×81481508² = 13278472291908128, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81481501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10185185 + ... + 10185192.

It is an arithmetic number, because the mean of its divisors is an integer number (23765441).

Almost surely, 2^81481508 is an apocalyptic number.

It is an amenable number.

81481508 is a deficient number, since it is larger than the sum of its proper divisors (61111138).

81481508 is a wasteful number, since it uses less digits than its factorization.

81481508 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20370381 (or 20370379 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 35.

The square root of 81481508 is about 9026.7108073761. The cubic root of 81481508 is about 433.5305293153.

The spelling of 81481508 in words is "eighty-one million, four hundred eighty-one thousand, five hundred eight".