378728621681 has 2 divisors, whose sum is σ = 378728621682. Its totient is φ = 378728621680.

The previous prime is 378728621639. The next prime is 378728621701. The reversal of 378728621681 is 186126827873.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 378728237281 + 384400 = 615409^2 + 620^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-378728621681 is a prime.

It is a super-2 number, since 2×378728621681² (a number of 24 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 378728621681.

It is not a weakly prime, because it can be changed into another prime (378728627681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 189364310840 + 189364310841.

It is an arithmetic number, because the mean of its divisors is an integer number (189364310841).

Almost surely, 2^378728621681 is an apocalyptic number.

It is an amenable number.

378728621681 is a deficient number, since it is larger than the sum of its proper divisors (1).

378728621681 is an equidigital number, since it uses as much as digits as its factorization.

378728621681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10838016, while the sum is 59.

The spelling of 378728621681 in words is "three hundred seventy-eight billion, seven hundred twenty-eight million, six hundred twenty-one thousand, six hundred eighty-one".