76810721 has 4 divisors (see below), whose sum is σ = 82719252. Its totient is φ = 70902192.

The previous prime is 76810717. The next prime is 76810729. The reversal of 76810721 is 12701867.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12701867 = 337 ⋅37691.

It can be written as a sum of positive squares in 2 ways, for example, as 11022400 + 65788321 = 3320^2 + 8111^2 .

It is a cyclic number.

It is not a de Polignac number, because 76810721 - 2² = 76810717 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (76810729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2954246 + ... + 2954271.

It is an arithmetic number, because the mean of its divisors is an integer number (20679813).

Almost surely, 2^76810721 is an apocalyptic number.

It is an amenable number.

76810721 is a deficient number, since it is larger than the sum of its proper divisors (5908531).

76810721 is a wasteful number, since it uses less digits than its factorization.

76810721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5908530.

The product of its (nonzero) digits is 4704, while the sum is 32.

The square root of 76810721 is about 8764.1725793140. The cubic root of 76810721 is about 425.0832058543.

The spelling of 76810721 in words is "seventy-six million, eight hundred ten thousand, seven hundred twenty-one".