16538777861 has 2 divisors, whose sum is σ = 16538777862. Its totient is φ = 16538777860.

The previous prime is 16538777837. The next prime is 16538777933. The reversal of 16538777861 is 16877783561.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16305757636 + 233020225 = 127694^2 + 15265^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16538777861 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 16538777861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16538777461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8269388930 + 8269388931.

It is an arithmetic number, because the mean of its divisors is an integer number (8269388931).

Almost surely, 2^16538777861 is an apocalyptic number.

It is an amenable number.

16538777861 is a deficient number, since it is larger than the sum of its proper divisors (1).

16538777861 is an equidigital number, since it uses as much as digits as its factorization.

16538777861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11854080, while the sum is 59.

The spelling of 16538777861 in words is "sixteen billion, five hundred thirty-eight million, seven hundred seventy-seven thousand, eight hundred sixty-one".