76816921 has 4 divisors (see below), whose sum is σ = 78893092. Its totient is φ = 74740752.

The previous prime is 76816913. The next prime is 76816967. The reversal of 76816921 is 12961867.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 56791296 + 20025625 = 7536^2 + 4475^2 .

It is a cyclic number.

It is not a de Polignac number, because 76816921 - 2³ = 76816913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (76816991) 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, 1038030 + ... + 1038103.

It is an arithmetic number, because the mean of its divisors is an integer number (19723273).

Almost surely, 2^76816921 is an apocalyptic number.

It is an amenable number.

76816921 is a deficient number, since it is larger than the sum of its proper divisors (2076171).

76816921 is a wasteful number, since it uses less digits than its factorization.

76816921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2076170.

The product of its digits is 36288, while the sum is 40.

The square root of 76816921 is about 8764.5262849740. The cubic root of 76816921 is about 425.0946428210.

It can be divided in two parts, 768 and 16921, that added together give a square (17689 = 133²).

The spelling of 76816921 in words is "seventy-six million, eight hundred sixteen thousand, nine hundred twenty-one".