806561890 has 16 divisors (see below), whose sum is σ = 1491050232. Its totient is φ = 313905024.

The previous prime is 806561869. The next prime is 806561911. The reversal of 806561890 is 98165608.

It is an interprime number because it is at equal distance from previous prime (806561869) and next prime (806561911).

It can be written as a sum of positive squares in 4 ways, for example, as 551169529 + 255392361 = 23477^2 + 15981^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1089579 + ... + 1090318.

Almost surely, 2^806561890 is an apocalyptic number.

806561890 is a deficient number, since it is larger than the sum of its proper divisors (684488342).

806561890 is a wasteful number, since it uses less digits than its factorization.

806561890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2179941.

The product of its (nonzero) digits is 103680, while the sum is 43.

The square root of 806561890 is about 28400.0332746284. The cubic root of 806561890 is about 930.8489915571.

The spelling of 806561890 in words is "eight hundred six million, five hundred sixty-one thousand, eight hundred ninety".