1780521664445 has 16 divisors (see below), whose sum is σ = 2178503410608. Its totient is φ = 1396646384640.

The previous prime is 1780521664387. The next prime is 1780521664447. The reversal of 1780521664445 is 5444661250871.

It can be written as a sum of positive squares in 8 ways, for example, as 824948943289 + 955572721156 = 908267^2 + 977534^2 .

It is not a de Polignac number, because 1780521664445 - 2⁸ = 1780521664189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1780521664447) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9111164 + ... + 9304533.

It is an arithmetic number, because the mean of its divisors is an integer number (136156463163).

Almost surely, 2^{1780521664445} is an apocalyptic number.

It is an amenable number.

1780521664445 is a deficient number, since it is larger than the sum of its proper divisors (397981746163).

1780521664445 is a wasteful number, since it uses less digits than its factorization.

1780521664445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18416080.

The product of its (nonzero) digits is 6451200, while the sum is 53.

The spelling of 1780521664445 in words is "one trillion, seven hundred eighty billion, five hundred twenty-one million, six hundred sixty-four thousand, four hundred forty-five".