987640561 has 2 divisors, whose sum is σ = 987640562. Its totient is φ = 987640560.

The previous prime is 987640547. The next prime is 987640567. The reversal of 987640561 is 165046789.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 850305600 + 137334961 = 29160^2 + 11719^2 .

It is a cyclic number.

It is not a de Polignac number, because 987640561 - 2¹¹ = 987638513 is a prime.

It is not a weakly prime, because it can be changed into another prime (987640567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 493820280 + 493820281.

It is an arithmetic number, because the mean of its divisors is an integer number (493820281).

Almost surely, 2^987640561 is an apocalyptic number.

It is an amenable number.

987640561 is a deficient number, since it is larger than the sum of its proper divisors (1).

987640561 is an equidigital number, since it uses as much as digits as its factorization.

987640561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 362880, while the sum is 46.

The square root of 987640561 is about 31426.7491319099. The cubic root of 987640561 is about 995.8630966301.

The spelling of 987640561 in words is "nine hundred eighty-seven million, six hundred forty thousand, five hundred sixty-one".