81839897 has 16 divisors (see below), whose sum is σ = 89156160. Its totient is φ = 74872512.

The previous prime is 81839869. The next prime is 81839917. The reversal of 81839897 is 79893818.

It is a cyclic number.

It is not a de Polignac number, because 81839897 - 2¹² = 81835801 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (53).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81839867) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66863 + ... + 68075.

It is an arithmetic number, because the mean of its divisors is an integer number (5572260).

Almost surely, 2^81839897 is an apocalyptic number.

It is an amenable number.

81839897 is a deficient number, since it is larger than the sum of its proper divisors (7316263).

81839897 is a wasteful number, since it uses less digits than its factorization.

81839897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1352.

The product of its digits is 870912, while the sum is 53.

The square root of 81839897 is about 9046.5406095369. The cubic root of 81839897 is about 434.1652145517.

The spelling of 81839897 in words is "eighty-one million, eight hundred thirty-nine thousand, eight hundred ninety-seven".