81978260 has 96 divisors (see below), whose sum is σ = 218867712. Its totient is φ = 25090560.

The previous prime is 81978257. The next prime is 81978263. The reversal of 81978260 is 6287918.

It is an interprime number because it is at equal distance from previous prime (81978257) and next prime (81978263).

It is a super-2 number, since 2×81978260² = 13440870225255200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81978263) 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 31 ways as a sum of consecutive naturals, for example, 55694 + ... + 57146.

It is an arithmetic number, because the mean of its divisors is an integer number (2279872).

Almost surely, 2^81978260 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81978260, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109433856).

81978260 is an abundant number, since it is smaller than the sum of its proper divisors (136889452).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81978260 is a wasteful number, since it uses less digits than its factorization.

81978260 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1513 (or 1511 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 41.

The square root of 81978260 is about 9054.1846678760. The cubic root of 81978260 is about 434.4097512697.

The spelling of 81978260 in words is "eighty-one million, nine hundred seventy-eight thousand, two hundred sixty".