81978611 has 8 divisors (see below), whose sum is σ = 96310704. Its totient is φ = 68793120.

The previous prime is 81978593. The next prime is 81978613. The reversal of 81978611 is 11687918.

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

It is not a de Polignac number, because 81978611 - 2¹⁴ = 81962227 is a prime.

It is a super-2 number, since 2×81978611² = 13440985322978642, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81978613) 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, 286496 + ... + 286781.

It is an arithmetic number, because the mean of its divisors is an integer number (12038838).

Almost surely, 2^81978611 is an apocalyptic number.

81978611 is a deficient number, since it is larger than the sum of its proper divisors (14332093).

81978611 is a wasteful number, since it uses less digits than its factorization.

81978611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 573301.

The product of its digits is 24192, while the sum is 41.

The square root of 81978611 is about 9054.2040511577. The cubic root of 81978611 is about 434.4103712618.

The spelling of 81978611 in words is "eighty-one million, nine hundred seventy-eight thousand, six hundred eleven".