1187447561 has 2 divisors, whose sum is σ = 1187447562. Its totient is φ = 1187447560.

The previous prime is 1187447497. The next prime is 1187447567. The reversal of 1187447561 is 1657447811.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 740928400 + 446519161 = 27220^2 + 21131^2 .

It is a cyclic number.

It is not a de Polignac number, because 1187447561 - 2⁶ = 1187447497 is a prime.

It is not a weakly prime, because it can be changed into another prime (1187447567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 593723780 + 593723781.

It is an arithmetic number, because the mean of its divisors is an integer number (593723781).

Almost surely, 2^1187447561 is an apocalyptic number.

It is an amenable number.

1187447561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1187447561 is an equidigital number, since it uses as much as digits as its factorization.

1187447561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 188160, while the sum is 44.

The square root of 1187447561 is about 34459.3610068440. The cubic root of 1187447561 is about 1058.9403083007.

The spelling of 1187447561 in words is "one billion, one hundred eighty-seven million, four hundred forty-seven thousand, five hundred sixty-one".