81751961929 has 45 divisors (see below), whose sum is σ = 96219757335. Its totient is φ = 69444978240.

The previous prime is 81751961899. The next prime is 81751961947. The reversal of 81751961929 is 92916915718.

The square root of 81751961929 is 285923.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 63647721225 + 18104240704 = 252285^2 + 134552^2 .

It is a de Polignac number, because none of the positive numbers 2^k-81751961929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81751961989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 588143542 + ... + 588143680.

Almost surely, 2^81751961929 is an apocalyptic number.

81751961929 is the 285923-rd square number.

81751961929 is the 142962-nd centered octagonal number.

It is an amenable number.

81751961929 is a deficient number, since it is larger than the sum of its proper divisors (14467795406).

81751961929 is an frugal number, since it uses more digits than its factorization.

81751961929 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 356 (or 167 counting only the distinct ones).

The product of its digits is 2449440, while the sum is 58.

The spelling of 81751961929 in words is "eighty-one billion, seven hundred fifty-one million, nine hundred sixty-one thousand, nine hundred twenty-nine".