81306251247 has 8 divisors (see below), whose sum is σ = 116747437744. Its totient is φ = 50034616128.

The previous prime is 81306251197. The next prime is 81306251291. The reversal of 81306251247 is 74215260318.

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

It is not a de Polignac number, because 81306251247 - 2¹⁵ = 81306218479 is a prime.

It is a super-2 number, since 2×81306251247² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39), and also a Moran number because the ratio is a prime number: 2084775673 = 81306251247 / (8 + 1 + 3 + 0 + 6 + 2 + 5 + 1 + 2 + 4 + 7).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81306251647) 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, 1042387798 + ... + 1042387875.

It is an arithmetic number, because the mean of its divisors is an integer number (14593429718).

Almost surely, 2^81306251247 is an apocalyptic number.

81306251247 is a deficient number, since it is larger than the sum of its proper divisors (35441186497).

81306251247 is a wasteful number, since it uses less digits than its factorization.

81306251247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2084775689.

The product of its (nonzero) digits is 80640, while the sum is 39.

The spelling of 81306251247 in words is "eighty-one billion, three hundred six million, two hundred fifty-one thousand, two hundred forty-seven".