81319284 has 36 divisors (see below), whose sum is σ = 205847460. Its totient is φ = 27068160.

The previous prime is 81319267. The next prime is 81319289. The reversal of 81319284 is 48291318.

It can be written as a sum of positive squares in 2 ways, for example, as 36723600 + 44595684 = 6060^2 + 6678^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×81319284² = 13225651900545312, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81319289) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 37132 + ... + 39260.

It is an arithmetic number, because the mean of its divisors is an integer number (5717985).

Almost surely, 2^81319284 is an apocalyptic number.

It is an amenable number.

81319284 is an abundant number, since it is smaller than the sum of its proper divisors (124528176).

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

81319284 is a wasteful number, since it uses less digits than its factorization.

81319284 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3200 (or 3195 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 81319284 is about 9017.7205545526. The cubic root of 81319284 is about 433.2426284839.

The spelling of 81319284 in words is "eighty-one million, three hundred nineteen thousand, two hundred eighty-four".