81213057329 has 8 divisors (see below), whose sum is σ = 81403097160. Its totient is φ = 81023072256.

The previous prime is 81213057307. The next prime is 81213057347. The reversal of 81213057329 is 92375031218.

It can be written as a sum of positive squares in 4 ways, for example, as 28988467600 + 52224589729 = 170260^2 + 228527^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 81213057329 - 2⁸ = 81213057073 is a prime.

It is a super-2 number, since 2×81213057329² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81213053329) 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, 5290337 + ... + 5305665.

It is an arithmetic number, because the mean of its divisors is an integer number (10175387145).

Almost surely, 2^81213057329 is an apocalyptic number.

It is an amenable number.

81213057329 is a deficient number, since it is larger than the sum of its proper divisors (190039831).

81213057329 is a wasteful number, since it uses less digits than its factorization.

81213057329 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27379.

The product of its (nonzero) digits is 90720, while the sum is 41.

The spelling of 81213057329 in words is "eighty-one billion, two hundred thirteen million, fifty-seven thousand, three hundred twenty-nine".