1855820221 has 8 divisors (see below), whose sum is σ = 1871783424. Its totient is φ = 1839892320.

The previous prime is 1855820207. The next prime is 1855820237. The reversal of 1855820221 is 1220285581.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1855820221 - 2⁵ = 1855820189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1855820201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 102756 + ... + 119458.

It is an arithmetic number, because the mean of its divisors is an integer number (233972928).

Almost surely, 2^1855820221 is an apocalyptic number.

It is an amenable number.

1855820221 is a deficient number, since it is larger than the sum of its proper divisors (15963203).

1855820221 is a wasteful number, since it uses less digits than its factorization.

1855820221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17651.

The product of its (nonzero) digits is 12800, while the sum is 34.

The square root of 1855820221 is about 43079.2318989092. The cubic root of 1855820221 is about 1228.8870495357.

The spelling of 1855820221 in words is "one billion, eight hundred fifty-five million, eight hundred twenty thousand, two hundred twenty-one".