1855355261 has 4 divisors (see below), whose sum is σ = 1855442400. Its totient is φ = 1855268124.

The previous prime is 1855355251. The next prime is 1855355279. The reversal of 1855355261 is 1625535581.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1855355261 - 2¹⁸ = 1855093117 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 (1855355251) 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, 11960 + ... + 62078.

It is an arithmetic number, because the mean of its divisors is an integer number (463860600).

Almost surely, 2^1855355261 is an apocalyptic number.

It is an amenable number.

1855355261 is a deficient number, since it is larger than the sum of its proper divisors (87139).

1855355261 is an equidigital number, since it uses as much as digits as its factorization.

1855355261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87138.

The product of its digits is 180000, while the sum is 41.

The square root of 1855355261 is about 43073.8349929513. The cubic root of 1855355261 is about 1228.7844118914.

The spelling of 1855355261 in words is "one billion, eight hundred fifty-five million, three hundred fifty-five thousand, two hundred sixty-one".