16749277561 has 3 divisors (see below), whose sum is σ = 16749406981. Its totient is φ = 16749148142.

The previous prime is 16749277547. The next prime is 16749277577. The reversal of 16749277561 is 16577294761.

The square root of 16749277561 is 129419.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 16577294761 = 38053 ⋅435637.

It is not a de Polignac number, because 16749277561 - 2¹⁷ = 16749146489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16749277541) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 64710 + ... + 194128.

Almost surely, 2^16749277561 is an apocalyptic number.

16749277561 is the 129419-th square number.

16749277561 is the 64710-th centered octagonal number.

It is an amenable number.

16749277561 is a deficient number, since it is larger than the sum of its proper divisors (129420).

16749277561 is an frugal number, since it uses more digits than its factorization.

16749277561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258838 (or 129419 counting only the distinct ones).

The product of its digits is 4445280, while the sum is 55.

The spelling of 16749277561 in words is "sixteen billion, seven hundred forty-nine million, two hundred seventy-seven thousand, five hundred sixty-one".