1928221987 has 2 divisors, whose sum is σ = 1928221988. Its totient is φ = 1928221986.

The previous prime is 1928221949. The next prime is 1928222057. The reversal of 1928221987 is 7891228291.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1928221987 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1928221987.

It is not a weakly prime, because it can be changed into another prime (1928221187) 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, 964110993 + 964110994.

It is an arithmetic number, because the mean of its divisors is an integer number (964110994).

Almost surely, 2^1928221987 is an apocalyptic number.

1928221987 is a deficient number, since it is larger than the sum of its proper divisors (1).

1928221987 is an equidigital number, since it uses as much as digits as its factorization.

1928221987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 290304, while the sum is 49.

The square root of 1928221987 is about 43911.5245351377. The cubic root of 1928221987 is about 1244.6646165744.

The spelling of 1928221987 in words is "one billion, nine hundred twenty-eight million, two hundred twenty-one thousand, nine hundred eighty-seven".