80687821 has 4 divisors (see below), whose sum is σ = 81229500. Its totient is φ = 80146144.

The previous prime is 80687819. The next prime is 80687839. The reversal of 80687821 is 12878608.

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 29278921 + 51408900 = 5411^2 + 7170^2 .

It is a cyclic number.

It is not a de Polignac number, because 80687821 - 2¹ = 80687819 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (80687891) 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, 270616 + ... + 270913.

It is an arithmetic number, because the mean of its divisors is an integer number (20307375).

Almost surely, 2^80687821 is an apocalyptic number.

It is an amenable number.

80687821 is a deficient number, since it is larger than the sum of its proper divisors (541679).

80687821 is a wasteful number, since it uses less digits than its factorization.

80687821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 541678.

The product of its (nonzero) digits is 43008, while the sum is 40.

The square root of 80687821 is about 8982.6399794270. The cubic root of 80687821 is about 432.1183035763.

The spelling of 80687821 in words is "eighty million, six hundred eighty-seven thousand, eight hundred twenty-one".