81519609 has 8 divisors (see below), whose sum is σ = 112440960. Its totient is φ = 52472336.

The previous prime is 81519593. The next prime is 81519617. The reversal of 81519609 is 90691518.

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 81519609 - 2⁴ = 81519593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81519619) 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, 468417 + ... + 468590.

It is an arithmetic number, because the mean of its divisors is an integer number (14055120).

Almost surely, 2^81519609 is an apocalyptic number.

It is an amenable number.

81519609 is a deficient number, since it is larger than the sum of its proper divisors (30921351).

81519609 is a wasteful number, since it uses less digits than its factorization.

81519609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 937039.

The product of its (nonzero) digits is 19440, while the sum is 39.

The square root of 81519609 is about 9028.8210193801. The cubic root of 81519609 is about 433.5980921818.

It can be divided in two parts, 81519 and 609, that added together give a palindrome (82128).

The spelling of 81519609 in words is "eighty-one million, five hundred nineteen thousand, six hundred nine".