81615305 has 4 divisors (see below), whose sum is σ = 97938372. Its totient is φ = 65292240.

The previous prime is 81615299. The next prime is 81615307. The reversal of 81615305 is 50351618.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20322064 + 61293241 = 4508^2 + 7829^2 .

It is not a de Polignac number, because 81615305 - 2⁸ = 81615049 is a prime.

It is a super-2 number, since 2×81615305² = 13322116020486050, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81615307) 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, 8161526 + ... + 8161535.

It is an arithmetic number, because the mean of its divisors is an integer number (24484593).

Almost surely, 2^81615305 is an apocalyptic number.

It is an amenable number.

81615305 is a deficient number, since it is larger than the sum of its proper divisors (16323067).

81615305 is a wasteful number, since it uses less digits than its factorization.

81615305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16323066.

The product of its (nonzero) digits is 3600, while the sum is 29.

The square root of 81615305 is about 9034.1189387787. The cubic root of 81615305 is about 433.7676930000.

The spelling of 81615305 in words is "eighty-one million, six hundred fifteen thousand, three hundred five".