81299751 has 8 divisors (see below), whose sum is σ = 116738160. Its totient is φ = 50030592.

The previous prime is 81299747. The next prime is 81299753. The reversal of 81299751 is 15799218.

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

It is not a de Polignac number, because 81299751 - 2² = 81299747 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81299753) 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, 1042266 + ... + 1042343.

It is an arithmetic number, because the mean of its divisors is an integer number (14592270).

Almost surely, 2^81299751 is an apocalyptic number.

81299751 is a deficient number, since it is larger than the sum of its proper divisors (35438409).

81299751 is a wasteful number, since it uses less digits than its factorization.

81299751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2084625.

The product of its digits is 45360, while the sum is 42.

The square root of 81299751 is about 9016.6374552823. The cubic root of 81299751 is about 433.2079372212.

The spelling of 81299751 in words is "eighty-one million, two hundred ninety-nine thousand, seven hundred fifty-one".