781978133 has 2 divisors, whose sum is σ = 781978134. Its totient is φ = 781978132.

The previous prime is 781978123. The next prime is 781978157. The reversal of 781978133 is 331879187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 722641924 + 59336209 = 26882^2 + 7703^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-781978133 is a prime.

It is a super-2 number, since 2×781978133² = 1222979600980331378, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (781978123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390989066 + 390989067.

It is an arithmetic number, because the mean of its divisors is an integer number (390989067).

Almost surely, 2^781978133 is an apocalyptic number.

It is an amenable number.

781978133 is a deficient number, since it is larger than the sum of its proper divisors (1).

781978133 is an equidigital number, since it uses as much as digits as its factorization.

781978133 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 254016, while the sum is 47.

The square root of 781978133 is about 27963.8719243241. The cubic root of 781978133 is about 921.2939154043.

The spelling of 781978133 in words is "seven hundred eighty-one million, nine hundred seventy-eight thousand, one hundred thirty-three".