1921420409 has 2 divisors, whose sum is σ = 1921420410. Its totient is φ = 1921420408.

The previous prime is 1921420399. The next prime is 1921420453. The reversal of 1921420409 is 9040241291.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1219965184 + 701455225 = 34928^2 + 26485^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1921420409 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1921420009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 960710204 + 960710205.

It is an arithmetic number, because the mean of its divisors is an integer number (960710205).

Almost surely, 2^1921420409 is an apocalyptic number.

It is an amenable number.

1921420409 is a deficient number, since it is larger than the sum of its proper divisors (1).

1921420409 is an equidigital number, since it uses as much as digits as its factorization.

1921420409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 1921420409 is about 43834.0097298890. The cubic root of 1921420409 is about 1243.1994227350.

The spelling of 1921420409 in words is "one billion, nine hundred twenty-one million, four hundred twenty thousand, four hundred nine".