1987775761 has 2 divisors, whose sum is σ = 1987775762. Its totient is φ = 1987775760.

The previous prime is 1987775743. The next prime is 1987775807. The reversal of 1987775761 is 1675777891.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1444000000 + 543775761 = 38000^2 + 23319^2 .

It is a cyclic number.

It is not a de Polignac number, because 1987775761 - 2¹⁷ = 1987644689 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1987775696 and 1987775705.

It is not a weakly prime, because it can be changed into another prime (1987775261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 993887880 + 993887881.

It is an arithmetic number, because the mean of its divisors is an integer number (993887881).

Almost surely, 2^1987775761 is an apocalyptic number.

It is an amenable number.

1987775761 is a deficient number, since it is larger than the sum of its proper divisors (1).

1987775761 is an equidigital number, since it uses as much as digits as its factorization.

1987775761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5186160, while the sum is 58.

The square root of 1987775761 is about 44584.4789248456. The cubic root of 1987775761 is about 1257.3488729317.

The spelling of 1987775761 in words is "one billion, nine hundred eighty-seven million, seven hundred seventy-five thousand, seven hundred sixty-one".