16687576981 has 6 divisors (see below), whose sum is σ = 17282854082. Its totient is φ = 16112142480.

The previous prime is 16687576967. The next prime is 16687576987. The reversal of 16687576981 is 18967578661.

It can be written as a sum of positive squares in 3 ways, for example, as 7720433956 + 8967143025 = 87866^2 + 94695^2 .

It is not a de Polignac number, because 16687576981 - 2⁷ = 16687576853 is a prime.

It is a super-2 number, since 2×16687576981² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16687576987) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 9920430 + ... + 9922111.

Almost surely, 2^16687576981 is an apocalyptic number.

It is an amenable number.

16687576981 is a deficient number, since it is larger than the sum of its proper divisors (595277101).

16687576981 is an equidigital number, since it uses as much as digits as its factorization.

16687576981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19842599 (or 19842570 counting only the distinct ones).

The product of its digits is 30481920, while the sum is 64.

The spelling of 16687576981 in words is "sixteen billion, six hundred eighty-seven million, five hundred seventy-six thousand, nine hundred eighty-one".