1999971553 has 2 divisors, whose sum is σ = 1999971554. Its totient is φ = 1999971552.

The previous prime is 1999971551. The next prime is 1999971563. The reversal of 1999971553 is 3551799991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1988089744 + 11881809 = 44588^2 + 3447^2 .

It is an emirp because it is prime and its reverse (3551799991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1999971553 - 2¹ = 1999971551 is a prime.

Together with 1999971551, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1999971551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999985776 + 999985777.

It is an arithmetic number, because the mean of its divisors is an integer number (999985777).

Almost surely, 2^1999971553 is an apocalyptic number.

It is an amenable number.

1999971553 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999971553 is an equidigital number, since it uses as much as digits as its factorization.

1999971553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3444525, while the sum is 58.

The square root of 1999971553 is about 44721.0415017361. The cubic root of 1999971553 is about 1259.9150763709.

The spelling of 1999971553 in words is "one billion, nine hundred ninety-nine million, nine hundred seventy-one thousand, five hundred fifty-three".