76695209721 has 81 divisors (see below), whose sum is σ = 125042097999. Its totient is φ = 47017595664.

The previous prime is 76695209719. The next prime is 76695209743. The reversal of 76695209721 is 12790259667.

The square root of 76695209721 is 276939.

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

76695209721 is a `hidden beast` number, since 7 + 6 + 6 + 9 + 520 + 97 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 11345445225 + 65349764496 = 106515^2 + 255636^2 .

It is a tau number, because it is divible by the number of its divisors (81).

It is not a de Polignac number, because 76695209721 - 2¹ = 76695209719 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 (76695209771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 291616636 + ... + 291616898.

Almost surely, 2^76695209721 is an apocalyptic number.

76695209721 is the 276939-th square number.

76695209721 is the 138470-th centered octagonal number.

It is an amenable number.

76695209721 is a deficient number, since it is larger than the sum of its proper divisors (48346888278).

76695209721 is an frugal number, since it uses more digits than its factorization.

76695209721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 576 (or 279 counting only the distinct ones).

The product of its (nonzero) digits is 2857680, while the sum is 54.

The spelling of 76695209721 in words is "seventy-six billion, six hundred ninety-five million, two hundred nine thousand, seven hundred twenty-one".