81757920682 has 8 divisors (see below), whose sum is σ = 122641551396. Its totient is φ = 40877403552.

The previous prime is 81757920661. The next prime is 81757920697. The reversal of 81757920682 is 28602975718.

It can be written as a sum of positive squares in 2 ways, for example, as 81521099361 + 236821321 = 285519^2 + 15389^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 711603 + ... + 818470.

Almost surely, 2^81757920682 is an apocalyptic number.

81757920682 is a deficient number, since it is larger than the sum of its proper divisors (40883630714).

81757920682 is a wasteful number, since it uses less digits than its factorization.

81757920682 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1556792.

The product of its (nonzero) digits is 3386880, while the sum is 55.

The spelling of 81757920682 in words is "eighty-one billion, seven hundred fifty-seven million, nine hundred twenty thousand, six hundred eighty-two".