1855921 has 2 divisors, whose sum is σ = 1855922. Its totient is φ = 1855920.

The previous prime is 1855891. The next prime is 1855927. The reversal of 1855921 is 1295581.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1852321 + 3600 = 1361^2 + 60^2 .

It is a cyclic number.

It is not a de Polignac number, because 1855921 - 2¹⁵ = 1823153 is a prime.

It is an Ulam number.

It is equal to p₁₃₈₉₆₄ and since 1855921 and 138964 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (1855927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 927960 + 927961.

It is an arithmetic number, because the mean of its divisors is an integer number (927961).

2^1855921 is an apocalyptic number.

It is an amenable number.

1855921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1855921 is an equidigital number, since it uses as much as digits as its factorization.

1855921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3600, while the sum is 31.

The square root of 1855921 is about 1362.3219149672. The cubic root of 1855921 is about 122.8909293746.

Subtracting from 1855921 its product of digits (3600), we obtain a square (1852321 = 1361²).

The spelling of 1855921 in words is "one million, eight hundred fifty-five thousand, nine hundred twenty-one".