8387491661 has 2 divisors, whose sum is σ = 8387491662. Its totient is φ = 8387491660.

The previous prime is 8387491649. The next prime is 8387491691. The reversal of 8387491661 is 1661947838.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7640508100 + 746983561 = 87410^2 + 27331^2 .

It is a cyclic number.

It is not a de Polignac number, because 8387491661 - 2²⁶ = 8320382797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8387491691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4193745830 + 4193745831.

It is an arithmetic number, because the mean of its divisors is an integer number (4193745831).

Almost surely, 2^8387491661 is an apocalyptic number.

It is an amenable number.

8387491661 is a deficient number, since it is larger than the sum of its proper divisors (1).

8387491661 is an equidigital number, since it uses as much as digits as its factorization.

8387491661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1741824, while the sum is 53.

The square root of 8387491661 is about 91583.2498931983. The cubic root of 8387491661 is about 2031.7832099879.

The spelling of 8387491661 in words is "eight billion, three hundred eighty-seven million, four hundred ninety-one thousand, six hundred sixty-one".