1921405729 has 2 divisors, whose sum is σ = 1921405730. Its totient is φ = 1921405728.

The previous prime is 1921405697. The next prime is 1921405747. The reversal of 1921405729 is 9275041291.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1779152400 + 142253329 = 42180^2 + 11927^2 .

It is an emirp because it is prime and its reverse (9275041291) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1921405729 - 2⁵ = 1921405697 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1921405691 and 1921405700.

It is not a weakly prime, because it can be changed into another prime (1921405529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 960702864 + 960702865.

It is an arithmetic number, because the mean of its divisors is an integer number (960702865).

Almost surely, 2^1921405729 is an apocalyptic number.

It is an amenable number.

1921405729 is a deficient number, since it is larger than the sum of its proper divisors (1).

1921405729 is an equidigital number, since it uses as much as digits as its factorization.

1921405729 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 45360, while the sum is 40.

The square root of 1921405729 is about 43833.8422796816. The cubic root of 1921405729 is about 1243.1962566373.

The spelling of 1921405729 in words is "one billion, nine hundred twenty-one million, four hundred five thousand, seven hundred twenty-nine".