81516744 has 24 divisors (see below), whose sum is σ = 220774710. Its totient is φ = 27172224.

The previous prime is 81516739. The next prime is 81516749. The reversal of 81516744 is 44761518.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81516739) and next prime (81516749).

It can be written as a sum of positive squares in only one way, i.e., 41447844 + 40068900 = 6438^2 + 6330^2 .

It is a tau number, because it is divible by the number of its divisors (24).

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

It is a junction number, because it is equal to n+sod(n) for n = 81516699 and 81516708.

It is not an unprimeable number, because it can be changed into a prime (81516749) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 566017 + ... + 566160.

Almost surely, 2^81516744 is an apocalyptic number.

It is an amenable number.

81516744 is an abundant number, since it is smaller than the sum of its proper divisors (139257966).

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

81516744 is a wasteful number, since it uses less digits than its factorization.

81516744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1132189 (or 1132182 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 81516744 is about 9028.6623593974. The cubic root of 81516744 is about 433.5930125325.

The spelling of 81516744 in words is "eighty-one million, five hundred sixteen thousand, seven hundred forty-four".