1987554221 has 2 divisors, whose sum is σ = 1987554222. Its totient is φ = 1987554220.

The previous prime is 1987554209. The next prime is 1987554227. The reversal of 1987554221 is 1224557891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1897038025 + 90516196 = 43555^2 + 9514^2 .

It is a cyclic number.

It is not a de Polignac number, because 1987554221 - 2⁶ = 1987554157 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1987554227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 993777110 + 993777111.

It is an arithmetic number, because the mean of its divisors is an integer number (993777111).

Almost surely, 2^1987554221 is an apocalyptic number.

It is an amenable number.

1987554221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1987554221 is an equidigital number, since it uses as much as digits as its factorization.

1987554221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 201600, while the sum is 44.

The square root of 1987554221 is about 44581.9943587094. The cubic root of 1987554221 is about 1257.3021601814.

The spelling of 1987554221 in words is "one billion, nine hundred eighty-seven million, five hundred fifty-four thousand, two hundred twenty-one".