15661554449 has 2 divisors, whose sum is σ = 15661554450. Its totient is φ = 15661554448.

The previous prime is 15661554443. The next prime is 15661554457. The reversal of 15661554449 is 94445516651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15270780625 + 390773824 = 123575^2 + 19768^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15661554449 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 15661554397 and 15661554406.

It is not a weakly prime, because it can be changed into another prime (15661554443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7830777224 + 7830777225.

It is an arithmetic number, because the mean of its divisors is an integer number (7830777225).

Almost surely, 2^15661554449 is an apocalyptic number.

It is an amenable number.

15661554449 is a deficient number, since it is larger than the sum of its proper divisors (1).

15661554449 is an equidigital number, since it uses as much as digits as its factorization.

15661554449 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592000, while the sum is 50.

The spelling of 15661554449 in words is "fifteen billion, six hundred sixty-one million, five hundred fifty-four thousand, four hundred forty-nine".