812685221 has 4 divisors (see below), whose sum is σ = 860490252. Its totient is φ = 764880192.

The previous prime is 812685217. The next prime is 812685229. The reversal of 812685221 is 122586218.

It is a happy number.

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 310252996 + 502432225 = 17614^2 + 22415^2 .

It is a cyclic number.

It is not a de Polignac number, because 812685221 - 2² = 812685217 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (812685229) 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, 23902490 + ... + 23902523.

It is an arithmetic number, because the mean of its divisors is an integer number (215122563).

Almost surely, 2^812685221 is an apocalyptic number.

It is an amenable number.

812685221 is a deficient number, since it is larger than the sum of its proper divisors (47805031).

812685221 is a wasteful number, since it uses less digits than its factorization.

812685221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47805030.

The product of its digits is 15360, while the sum is 35.

The square root of 812685221 is about 28507.6344336039. The cubic root of 812685221 is about 933.1986904271.

The spelling of 812685221 in words is "eight hundred twelve million, six hundred eighty-five thousand, two hundred twenty-one".