781327501921 has 2 divisors, whose sum is σ = 781327501922. Its totient is φ = 781327501920.

The previous prime is 781327501901. The next prime is 781327501931. The reversal of 781327501921 is 129105723187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 725801763600 + 55525738321 = 851940^2 + 235639^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-781327501921 is a prime.

It is a super-2 number, since 2×781327501921² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (781327501901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390663750960 + 390663750961.

It is an arithmetic number, because the mean of its divisors is an integer number (390663750961).

Almost surely, 2^781327501921 is an apocalyptic number.

It is an amenable number.

781327501921 is a deficient number, since it is larger than the sum of its proper divisors (1).

781327501921 is an equidigital number, since it uses as much as digits as its factorization.

781327501921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 211680, while the sum is 46.

The spelling of 781327501921 in words is "seven hundred eighty-one billion, three hundred twenty-seven million, five hundred one thousand, nine hundred twenty-one".