81544915 has 8 divisors (see below), whose sum is σ = 98953920. Its totient is φ = 64502592.

The previous prime is 81544909. The next prime is 81544919. The reversal of 81544915 is 51944518.

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 81544915 - 2⁹ = 81544403 is a prime.

It is a super-3 number, since 3×81544915³ (a number of 25 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (81544919) 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, 91179 + ... + 92068.

It is an arithmetic number, because the mean of its divisors is an integer number (12369240).

Almost surely, 2^81544915 is an apocalyptic number.

81544915 is a deficient number, since it is larger than the sum of its proper divisors (17409005).

81544915 is a wasteful number, since it uses less digits than its factorization.

81544915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183341.

The product of its digits is 28800, while the sum is 37.

The square root of 81544915 is about 9030.2223117706. Note that the first 3 decimals coincide. The cubic root of 81544915 is about 433.6429545908.

The spelling of 81544915 in words is "eighty-one million, five hundred forty-four thousand, nine hundred fifteen".