15661246987 has 4 divisors (see below), whose sum is σ = 15994465056. Its totient is φ = 15328028920.

The previous prime is 15661246943. The next prime is 15661246999. The reversal of 15661246987 is 78964216651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78964216651 = 92203 ⋅856417.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15661246987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15661243987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166608964 + ... + 166609057.

It is an arithmetic number, because the mean of its divisors is an integer number (3998616264).

Almost surely, 2^15661246987 is an apocalyptic number.

15661246987 is a deficient number, since it is larger than the sum of its proper divisors (333218069).

15661246987 is an equidigital number, since it uses as much as digits as its factorization.

15661246987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333218068.

The product of its digits is 4354560, while the sum is 55.

The spelling of 15661246987 in words is "fifteen billion, six hundred sixty-one million, two hundred forty-six thousand, nine hundred eighty-seven".