787878781 has 2 divisors, whose sum is σ = 787878782. Its totient is φ = 787878780.

The previous prime is 787878769. The next prime is 787878797. The reversal of 787878781 is 187878787.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 720063556 + 67815225 = 26834^2 + 8235^2 .

It is a cyclic number.

It is not a de Polignac number, because 787878781 - 2²¹ = 785781629 is a prime.

It is a super-2 number, since 2×787878781² = 1241505947100091922, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (787870781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 393939390 + 393939391.

It is an arithmetic number, because the mean of its divisors is an integer number (393939391).

Almost surely, 2^787878781 is an apocalyptic number.

It is an amenable number.

787878781 is a deficient number, since it is larger than the sum of its proper divisors (1).

787878781 is an equidigital number, since it uses as much as digits as its factorization.

787878781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9834496, while the sum is 61.

The square root of 787878781 is about 28069.1784881567. The cubic root of 787878781 is about 923.6054099504.

The spelling of 787878781 in words is "seven hundred eighty-seven million, eight hundred seventy-eight thousand, seven hundred eighty-one".