16441521781 has 2 divisors, whose sum is σ = 16441521782. Its totient is φ = 16441521780.

The previous prime is 16441521773. The next prime is 16441521793. The reversal of 16441521781 is 18712514461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12816277681 + 3625244100 = 113209^2 + 60210^2 .

It is a cyclic number.

It is not a de Polignac number, because 16441521781 - 2³ = 16441521773 is a prime.

It is a super-5 number, since 5×16441521781⁵ (a number of 52 digits) contains 55555 as substring. Note that it is a super-d number also for d = 3, 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16441521281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8220760890 + 8220760891.

It is an arithmetic number, because the mean of its divisors is an integer number (8220760891).

Almost surely, 2^16441521781 is an apocalyptic number.

It is an amenable number.

16441521781 is a deficient number, since it is larger than the sum of its proper divisors (1).

16441521781 is an equidigital number, since it uses as much as digits as its factorization.

16441521781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 53760, while the sum is 40.

The spelling of 16441521781 in words is "sixteen billion, four hundred forty-one million, five hundred twenty-one thousand, seven hundred eighty-one".