1987554649 has 2 divisors, whose sum is σ = 1987554650. Its totient is φ = 1987554648.

The previous prime is 1987554631. The next prime is 1987554671. The reversal of 1987554649 is 9464557891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1328092249 + 659462400 = 36443^2 + 25680^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1987554649 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1987554593 and 1987554602.

It is not a weakly prime, because it can be changed into another prime (1987554619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 993777324 + 993777325.

It is an arithmetic number, because the mean of its divisors is an integer number (993777325).

Almost surely, 2^1987554649 is an apocalyptic number.

It is an amenable number.

1987554649 is a deficient number, since it is larger than the sum of its proper divisors (1).

1987554649 is an equidigital number, since it uses as much as digits as its factorization.

1987554649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10886400, while the sum is 58.

The square root of 1987554649 is about 44581.9991588533. Note that the first 3 decimals coincide. The cubic root of 1987554649 is about 1257.3022504305.

The spelling of 1987554649 in words is "one billion, nine hundred eighty-seven million, five hundred fifty-four thousand, six hundred forty-nine".