781649369 has 2 divisors, whose sum is σ = 781649370. Its totient is φ = 781649368.

The previous prime is 781649333. The next prime is 781649371. The reversal of 781649369 is 963946187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 718240000 + 63409369 = 26800^2 + 7963^2 .

It is a cyclic number.

It is not a de Polignac number, because 781649369 - 2¹² = 781645273 is a prime.

It is a super-2 number, since 2×781649369² = 1221951472116196322, which contains 22 as substring.

Together with 781649371, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 781649369.

It is not a weakly prime, because it can be changed into another prime (781649389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390824684 + 390824685.

It is an arithmetic number, because the mean of its divisors is an integer number (390824685).

Almost surely, 2^781649369 is an apocalyptic number.

It is an amenable number.

781649369 is a deficient number, since it is larger than the sum of its proper divisors (1).

781649369 is an equidigital number, since it uses as much as digits as its factorization.

781649369 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1959552, while the sum is 53.

The square root of 781649369 is about 27957.9929358314. The cubic root of 781649369 is about 921.1647853100.

The spelling of 781649369 in words is "seven hundred eighty-one million, six hundred forty-nine thousand, three hundred sixty-nine".