1906125721 has 2 divisors, whose sum is σ = 1906125722. Its totient is φ = 1906125720.

The previous prime is 1906125719. The next prime is 1906125751. The reversal of 1906125721 is 1275216091.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1234538496 + 671587225 = 35136^2 + 25915^2 .

It is an emirp because it is prime and its reverse (1275216091) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1906125721 - 2¹ = 1906125719 is a prime.

Together with 1906125719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1906125751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 953062860 + 953062861.

It is an arithmetic number, because the mean of its divisors is an integer number (953062861).

Almost surely, 2^1906125721 is an apocalyptic number.

It is an amenable number.

1906125721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1906125721 is an equidigital number, since it uses as much as digits as its factorization.

1906125721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7560, while the sum is 34.

The square root of 1906125721 is about 43659.1997292667. The cubic root of 1906125721 is about 1239.8919696468.

The spelling of 1906125721 in words is "one billion, nine hundred six million, one hundred twenty-five thousand, seven hundred twenty-one".