81516445 has 16 divisors (see below), whose sum is σ = 104131440. Its totient is φ = 61046784.

The previous prime is 81516437. The next prime is 81516451. The reversal of 81516445 is 54461518.

It can be written as a sum of positive squares in 8 ways, for example, as 3829849 + 77686596 = 1957^2 + 8814^2 .

It is a cyclic number.

It is not a de Polignac number, because 81516445 - 2³ = 81516437 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81516445.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13921 + ... + 18889.

It is an arithmetic number, because the mean of its divisors is an integer number (6508215).

Almost surely, 2^81516445 is an apocalyptic number.

81516445 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81516445 is a deficient number, since it is larger than the sum of its proper divisors (22614995).

81516445 is a wasteful number, since it uses less digits than its factorization.

81516445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5184.

The product of its digits is 19200, while the sum is 34.

The square root of 81516445 is about 9028.6458010047. The cubic root of 81516445 is about 433.5924823982.

The spelling of 81516445 in words is "eighty-one million, five hundred sixteen thousand, four hundred forty-five".