81884865 has 8 divisors (see below), whose sum is σ = 131015808. Its totient is φ = 43671920.

The previous prime is 81884863. The next prime is 81884911. The reversal of 81884865 is 56848818.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81884865 - 2¹ = 81884863 is a prime.

It is a super-2 number, since 2×81884865² = 13410262232136450, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81884863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2729481 + ... + 2729510.

It is an arithmetic number, because the mean of its divisors is an integer number (16376976).

Almost surely, 2^81884865 is an apocalyptic number.

It is an amenable number.

81884865 is a deficient number, since it is larger than the sum of its proper divisors (49130943).

81884865 is a wasteful number, since it uses less digits than its factorization.

81884865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5458999.

The product of its digits is 491520, while the sum is 48.

The square root of 81884865 is about 9049.0256381557. The cubic root of 81884865 is about 434.2447192405.

The spelling of 81884865 in words is "eighty-one million, eight hundred eighty-four thousand, eight hundred sixty-five".