81016751 has 4 divisors (see below), whose sum is σ = 82157904. Its totient is φ = 79875600.

The previous prime is 81016739. The next prime is 81016753. The reversal of 81016751 is 15761018.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81016751 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81016753) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 570470 + ... + 570611.

It is an arithmetic number, because the mean of its divisors is an integer number (20539476).

Almost surely, 2^81016751 is an apocalyptic number.

81016751 is a deficient number, since it is larger than the sum of its proper divisors (1141153).

81016751 is a wasteful number, since it uses less digits than its factorization.

81016751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1141152.

The product of its (nonzero) digits is 1680, while the sum is 29.

The square root of 81016751 is about 9000.9305630029. The cubic root of 81016751 is about 432.7046951136.

Adding to 81016751 its reverse (15761018), we get a palindrome (96777769).

The spelling of 81016751 in words is "eighty-one million, sixteen thousand, seven hundred fifty-one".