81205977682 has 8 divisors (see below), whose sum is σ = 124779917052. Its totient is φ = 39612672000.

The previous prime is 81205977649. The next prime is 81205977691. The reversal of 81205977682 is 28677950218.

It can be written as a sum of positive squares in 2 ways, for example, as 65357433801 + 15848543881 = 255651^2 + 125891^2 .

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

It is a super-2 number, since 2×81205977682² (a number of 23 digits) contains 22 as substring.

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, 495158319 + ... + 495158482.

Almost surely, 2^81205977682 is an apocalyptic number.

81205977682 is a gapful number since it is divisible by the number (82) formed by its first and last digit.

81205977682 is a deficient number, since it is larger than the sum of its proper divisors (43573939370).

81205977682 is a wasteful number, since it uses less digits than its factorization.

81205977682 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 990316844.

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

The spelling of 81205977682 in words is "eighty-one billion, two hundred five million, nine hundred seventy-seven thousand, six hundred eighty-two".