81244779 has 64 divisors (see below), whose sum is σ = 144322560. Its totient is φ = 39381120.

The previous prime is 81244777. The next prime is 81244781. The reversal of 81244779 is 97744218.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81244777) and next prime (81244781).

It is not a de Polignac number, because 81244779 - 2¹ = 81244777 is a prime.

It is a super-2 number, since 2×81244779² = 13201428229517682, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81244779.

It is not an unprimeable number, because it can be changed into a prime (81244777) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 469537 + ... + 469709.

It is an arithmetic number, because the mean of its divisors is an integer number (2255040).

Almost surely, 2^81244779 is an apocalyptic number.

81244779 is a deficient number, since it is larger than the sum of its proper divisors (63077781).

81244779 is a wasteful number, since it uses less digits than its factorization.

81244779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320.

The product of its digits is 112896, while the sum is 42.

The square root of 81244779 is about 9013.5885750349. The cubic root of 81244779 is about 433.1102752730.

The spelling of 81244779 in words is "eighty-one million, two hundred forty-four thousand, seven hundred seventy-nine".