1921905 has 12 divisors (see below), whose sum is σ = 3331380. Its totient is φ = 1024992.

The previous prime is 1921889. The next prime is 1921919. The reversal of 1921905 is 5091291.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 567009 + 1354896 = 753^2 + 1164^2 .

It is not a de Polignac number, because 1921905 - 2⁴ = 1921889 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21310 + ... + 21399.

It is an arithmetic number, because the mean of its divisors is an integer number (277615).

2^1921905 is an apocalyptic number.

1921905 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1921905 is a deficient number, since it is larger than the sum of its proper divisors (1409475).

1921905 is a wasteful number, since it uses less digits than its factorization.

1921905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42720 (or 42717 counting only the distinct ones).

The product of its (nonzero) digits is 810, while the sum is 27.

The square root of 1921905 is about 1386.3278832946. The cubic root of 1921905 is about 124.3303927474.

The spelling of 1921905 in words is "one million, nine hundred twenty-one thousand, nine hundred five".