16581877861 has 4 divisors (see below), whose sum is σ = 16597049932. Its totient is φ = 16566705792.

The previous prime is 16581877841. The next prime is 16581877867. The reversal of 16581877861 is 16877818561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16877818561 = 13913 ⋅1213097.

It can be written as a sum of positive squares in 2 ways, for example, as 16359689025 + 222188836 = 127905^2 + 14906^2 .

It is a cyclic number.

It is not a de Polignac number, because 16581877861 - 2¹⁹ = 16581353573 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16581877796 and 16581877805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16581877867) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7584396 + ... + 7586581.

It is an arithmetic number, because the mean of its divisors is an integer number (4149262483).

Almost surely, 2^16581877861 is an apocalyptic number.

It is an amenable number.

16581877861 is a deficient number, since it is larger than the sum of its proper divisors (15172071).

16581877861 is a wasteful number, since it uses less digits than its factorization.

16581877861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15172070.

The product of its digits is 4515840, while the sum is 58.

The spelling of 16581877861 in words is "sixteen billion, five hundred eighty-one million, eight hundred seventy-seven thousand, eight hundred sixty-one".