1897900721 has 2 divisors, whose sum is σ = 1897900722. Its totient is φ = 1897900720.

The previous prime is 1897900687. The next prime is 1897900733. The reversal of 1897900721 is 1270097981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1174021696 + 723879025 = 34264^2 + 26905^2 .

It is an emirp because it is prime and its reverse (1270097981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1897900721 - 2¹⁰ = 1897899697 is a prime.

It is not a weakly prime, because it can be changed into another prime (1897900751) 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, 948950360 + 948950361.

It is an arithmetic number, because the mean of its divisors is an integer number (948950361).

Almost surely, 2^1897900721 is an apocalyptic number.

It is an amenable number.

1897900721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1897900721 is an equidigital number, since it uses as much as digits as its factorization.

1897900721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 63504, while the sum is 44.

The square root of 1897900721 is about 43564.9023986052. The cubic root of 1897900721 is about 1238.1060057573.

The spelling of 1897900721 in words is "one billion, eight hundred ninety-seven million, nine hundred thousand, seven hundred twenty-one".