861800215 has 4 divisors (see below), whose sum is σ = 1034160264. Its totient is φ = 689440168.

The previous prime is 861800209. The next prime is 861800237. The reversal of 861800215 is 512008168.

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

It is a cyclic number.

It is not a de Polignac number, because 861800215 - 2³ = 861800207 is a prime.

It is a super-2 number, since 2×861800215² = 1485399221148092450, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) 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 an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86180017 + ... + 86180026.

It is an arithmetic number, because the mean of its divisors is an integer number (258540066).

Almost surely, 2^861800215 is an apocalyptic number.

861800215 is a deficient number, since it is larger than the sum of its proper divisors (172360049).

861800215 is a wasteful number, since it uses less digits than its factorization.

861800215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172360048.

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 861800215 is about 29356.4339625916. The cubic root of 861800215 is about 951.6316245209.

The spelling of 861800215 in words is "eight hundred sixty-one million, eight hundred thousand, two hundred fifteen".