81474839217 has 12 divisors (see below), whose sum is σ = 124608577860. Its totient is φ = 51121467648.

The previous prime is 81474839213. The next prime is 81474839219. The reversal of 81474839217 is 71293847418.

81474839217 is a `hidden beast` number, since 8 + 1 + 474 + 83 + 92 + 1 + 7 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 75141226161 + 6333613056 = 274119^2 + 79584^2 .

It is not a de Polignac number, because 81474839217 - 2² = 81474839213 is a prime.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (81474839213) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 266257492 + ... + 266257797.

It is an arithmetic number, because the mean of its divisors is an integer number (10384048155).

Almost surely, 2^81474839217 is an apocalyptic number.

It is an amenable number.

81474839217 is a deficient number, since it is larger than the sum of its proper divisors (43133738643).

81474839217 is a wasteful number, since it uses less digits than its factorization.

81474839217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 532515312 (or 532515309 counting only the distinct ones).

The product of its digits is 2709504, while the sum is 54.

The spelling of 81474839217 in words is "eighty-one billion, four hundred seventy-four million, eight hundred thirty-nine thousand, two hundred seventeen".