1981523923 has 2 divisors, whose sum is σ = 1981523924. Its totient is φ = 1981523922.

The previous prime is 1981523917. The next prime is 1981523959. The reversal of 1981523923 is 3293251891.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1981523923 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1981523923.

It is not a weakly prime, because it can be changed into another prime (1981523903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990761961 + 990761962.

It is an arithmetic number, because the mean of its divisors is an integer number (990761962).

Almost surely, 2^1981523923 is an apocalyptic number.

1981523923 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981523923 is an equidigital number, since it uses as much as digits as its factorization.

1981523923 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 116640, while the sum is 43.

The square root of 1981523923 is about 44514.3114402548. The cubic root of 1981523923 is about 1256.0293081031.

The spelling of 1981523923 in words is "one billion, nine hundred eighty-one million, five hundred twenty-three thousand, nine hundred twenty-three".